I thought I'd post a separate topic for my final findings on ripping mixed mode CDs to disk images in OS X. Mixed Mode CDs are rare these days and there's not a lot of good, centralized information on the internet for doing this. I know that certain popular search engines do a great job of indexing this forum, so hopefully this will show up for anyone hoping to get at this information in the future.

Here are the tools we'll be using:
XCode
MacPorts
cdrdao (compiled/installed via MacPorts)
toc2cue (gets compiled when you make cdrdao)
bchunk

STEPS:
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1. INSTALL XCODE
You can find XCode here: http://developer.apple.com/xcode/. I believe that XCode also ships on the "Applications" disc that comes with every Mac. XCode is the official Apple Development Environment and is needed to install things via MacPorts (actually, you compile them locally, but don't be scared, it's super easy). Please keep in mind that as of this writing XCode 4 is brand new but only supports OS X 10.6 and up. If you have OS X 10.5 or prior, you will need an earlier version of XCode.

2. INSTALL MACPORTS
Installation instructions for MacPorts are here: http://www.macports.org/install.php. MacPorts is a very cool system for compiling and installing open source software that is mostly developed by the Linux community but ported and maintained by OS X enthusiasts. It does require that you have some familiarity with using Terminal (the OS X command line app), but you can fumble your way around pretty easily even if you're not well-versed in it.

3. INSTALL CDRDAO
a) After your MacPorts installation has completed, open a Terminal window (Terminal can be found in Applications->Utilities).

b) In the Terminal window, type: "port install cdrdao" (without the quotation marks). You may need to run the program with administrator access, so it's possible you will have to type "sudo port install cdrdao" instead. Sudo will prompt you for your password as necessary. Be careful with sudo - you are giving any program you run with sudo full access to your system, so don't throw sudo around carelessly.

c) MacPorts will download all the necessary files and project dependencies, kick off the compilation of cdrdao and any dependencies, and generally do all the work for you. By the time you grab a snack and a soda cdrdao will probably be finished.

IMPORTANT NOTE: As of the time of this writing cdrdao's latest version is 1.2.3_0. This version has a bug that may keep it from properly accessing the optical drive. You may need to use cdrdao 1.2.2_2. This link explains how to install older versions of ports with MacPorts: http://trac.macports.org/wiki/howto/InstallingOlderPort

4. [OPTIONAL] INSTALL BCHUNK
Once cdrdao is installed, go through the same process with bchunk. You will type into your terminal window: "port install bchunk" (again, without the quotations). You will need bchunk if you ever want to access the .bin/.cue data in OS X (at least, if you want to access it without paying for fancy software to do so).

5. INSERT YOUR MIXED MODE CD AND UNMOUNT IT
a) The first part is obvious. Make sure your mixed mode CD is in the drive.
b) In order for cdrdao to do it's job, the disc has to be unmounted (but obviously, NOT ejected). I've shamelessly ripped these instructions from the DOSBox wiki (http://www.dosbox.com/wiki/Cuesheet).

In Terminal, type:
disktool -u disk3
disk3 device will be unmounted ...
***Notifications Complete for type 1
***Responding yes to unmount - disk3s0
***Disk Unmounted('disk3s0')
***Responding yes to unmount - disk3
***Disk Unmounted('disk3')

Substitute the appropriate disk for "disk3". You can find out which diskX block device corresponds to your CD or DVD drive by using the "mount" command.

6. CREATE THE .BIN/.CUE IMAGE WITH CDRDAO
a) Once the disc is unmounted, type the following in Terminal:
cdrdao read-cd --datafile image.bin --driver generic-mmc:0x20000 --device IODVDServices/0 --read-raw image.toc

b) This creates the .bin file which has all of the same information that is on your disc, both the data track and all audio tracks. However, it makes a .toc file instead of a .cue file to go with it. Luckily, cdrdao includes an easy tool for converting the .toc to a .cue. In Terminal, type:
toc2cue image.toc image.cue

IMPORTANT NOTE: You may substitute whatever name you want for "image" in the above commands, but make sure that your .bin and .cue both have the same name. If you change the name of both after you've finished, you *MUST* also open the .cue file in a text editor and change the name in the header as well.

CONGRATULATIONS! You have just created your first .bin/.cue image. Archive the pair of files wherever you'd like. It might be a good idea to zip them both together just so they don't get separated somehow. Note that as of this writing I do not know of any method for mounting the .bin/.cue in OS X as if it were a disc. It seems that there are no OS X equivalents to DaemonTools or VirtualCloneDrive.

7. [OPTIONAL] CONVERT .BIN/.CUE WITH BCHUNK
If you ever want to get to the data in your .bin/.cue image again, you'll need bchunk in order to convert the data portion to an .iso. If you followed the optional step 4 above it should already be installed.

In Terminal, type:
bchunk -w image.bin image.cue outputfilename

Substitute the name of your .bin/.cue files for "image" and your "outputfilename" can be whatever you want. The "-w" switch ensures that bchunk will write the audio tracks out as .wav files instead of .cdr. The .wav format is just a little more handy.

There you have it: complete instructions for handling mixed mode CDs in OS X. Please let me know if you have any trouble with these directions and I'll update as necessary.


ADDENDUM FOR WINDOWS USERS:
In Windows, the process is far easier. ImgBurn will create the .bin/.cue for you with just a few mouseclicks. The .bin/.cue can then be mounted with tools such as DaemonTools or VirtualCloneDrive. I find it quite ironic. On the one hand you have OS X which has great native support for many disc image formats but has such poor support, first or third-party, for this particular one. On the other hand, you have Windows with almost no native support for disc images, but excellent third party support for practically any disc image format out there, including .bin/.cue. Oh well.

EDIT: The original discussion that led to this post can be found here: http://www.gog.com/en/forum/general/tech_question_how_do_you_back_up_your_mixed_mode_cds

A quick note on XCode, MacPorts, and getting intimidated...

This may seem like a lot of work just to get your mixed mode CD backed up, and XCode and MacPorts in particular may seem a little intimidating. Let me just assure you that it's all going to be "ok." In fact, there are a TON of really useful apps that you can get via MacPorts (a great example being Wine).

A full listing (by category) can be found at this page on the MacPorts website:
http://www.macports.org/ports.php

Trust me, you won't be sorry you did this. ^_^

FAQ
This post will be used for answering common questions that come up about this process. Hopefully there will be few.

1. Doesn't SimplyBurns do all of this for you anyway?
A: Mostly. It will create the .bin/.toc pair that cdrdao spits out, but then you'll still need the toc2cue tool that comes with cdrdao to end up with a .bin/.cue. For that reason, it makes the most sense to me to just use cdrdao for the whole process. If you're interested in SimplyBurns you can find it here: http://simplyburns.berlios.de/

2. So there's absolutely no way to mount .bin/.cue files in OS X?
A: I'm using Snow Leopard and as far as I know there is no way to mount them directly into the OS X system. However, if your .bin/.cue image is the CD for a DOS game, then you can mount the .bin/.cue image in DOSBox and use it as a virtual drive within DOSBox.

I've been adding BIN/CUE ripping to Boxer using cdrdao, and from my own experiences I have a clarification to add regarding the cdrdao --device parameter:

6. CREATE THE .BIN/.CUE IMAGE WITH CDRDAO
a) Once the disc is unmounted, type the following in Terminal:
cdrdao read-cd --datafile image.bin --driver generic-mmc:0x20000 --device IODVDServices/0 --read-raw image.toc

The "IODVDServices/0" device ID will vary depending on the actual device, and at least in cdrdao 1.2.3 it actually needs to be a much longer and more complex string (perhaps this is what you were alluding to as a bug in 1.2.3?) Anyway, in any version of cdrdao you can find the right device ID for your DVD drive by running the following command:

sudo cdrdao scanbus

This will prompt you to enter your administrator password and will then list out all the CD/DVD-burning devices available on your system, with the device ID you'll need to feed to the read-cd command.

If you get a very long device ID then I recommend wrapping it in "" quotation marks when feeding it as the --device parameter, since it may contain spaces. For instance:

cdrdao read-cd --datafile image.bin --driver generic-mmc:0x20000 --device "IOService:/AppleACPIPlatformExpert/PCI0@0/AppleACPIPCI/SATA@B/AppleMCP79AHCI/PRT1@1/IOAHCIDevice@0/IOAHCISeri alATAPI/IOSCSIPeripheralDeviceNub/IOSCSIPeripheralDeviceType05/IODVDServices" --read-raw image.toc

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On another note, I recommend using homebrew as an alternative to Macports. I've had problems installing some packages with it, but on the whole it's just much, much friendlier than macports. With homebrew, the commands would just be "brew install cdrdao" and "brew install bchunk" instead.

(edited to correct formatting)

Awesome! Thanks for the contribution!

I'll have to check out homebrew. I didn't even know it existed. ^_^

I just run Alcohol 120% in VirtualBox.

Another minor clarification:

In my own testing (cdrdao 1.2.3 on a Macbook Air with the external superdrive), the "cdrdao scanbus" command requires sudo if there's a CD already in the drive - without sudo, cdrdao complains about not being able to obtain exclusive access.

You can run the command without sudo as long as you do so before inserting the disc you're going to rip. That might come in useful for people running under a normal user account.