Ok everyone, I'm going to share how I was able to get Baldur's Gate Trilogy (BG1 using BG2 engine) successfully and relatively painlessly installed on my Macbook Pro with OSX Mavericks.
Step 0. Download the following files:
GOG Baldur's Gate 1 Complete Mac client
GOG Baldur's Gate 2 Complete WINDOWS VERSION (yes, Windows version. It's important later, you'll see why...)
Baldur's Gate Trilogy mod v1.18 (as of this writing), which can be found here:
shsforums (dot) net/files/file/54-baldurs-gate-trilogy-weidu/
Step 1. Do a clean, full installation of Baldur's Gate 1 as you normally would. Launch the game like normal, then exit out from the main menu.
Step 2. In Finder, navigate to your Applications folder, then right click on Baldur's Gate 1 and click "Show Package Contents." You'll see a file named "Wineskin," open it. Click on "Install Software." Point the installer to setup_baldurs_gate2.exe or whatever it's called (should be in your Downloads folder inside a file called Baldurs Gate 2 Complete). Note: This is the reason I had you download the Windows installer, because it's super easy to install via Wineskin. Once Baldur's Gate 2 has installed, you'll want to run the game and go through the setup process. You can accomplish that by setting Wineskin to run BGConfig.exe (right click BG1, show package contents, open Wineskin, click on Advanced, then under Windows EXE click "Browse" and point it to C:/GOG Games/Baldur's Gate 2/BGConfig.exe), then click "Test Run" at the bottom. Configure BG2 to your heart's content. Launch the game (point Wineskin launcher to run BGMain.exe in your BG2 file), then exit from the main menu.
Step 3. At this point you should be able to launch either game (BG1 or BG2) just by pointing Wineskin to the appropriate exe file. If so, great. If not, please make sure you installed the games the way I've instructed you to. Next, you're going to take the Baldur's Gate Trilogy mod (BGT118 or Weidu 1.18 whatever it's called) and extract it. Now, take the 3 files it extracted and Copy/Paste those inside your BG2 folder (once again, in Applications right click on BG1 -> show package content -> C:/GOG Games/Baldur's Gate 2).
Step 4. Navigate to C:/Windows/Command (you should still be inside your BG1 app folder anyways). You'll see a file called "Start.exe" (without quotes). Copy it (command-key + C or at the top of your screen click on Edit -> Copy) and paste the file in C:/GOG Games/Baldur's Gate 2 (command-key + V or Edit -> Paste).
Step 5. Go back to the BG1 Wineskin program (open it, click on Advanced). Point the exe launcher to the "start.exe" file you just pasted in your BG2 file (make sure the box is checked that says "use Start.exe"), and launch it by clicking "Test Run." Wineskin will open up a command prompt showing something like C:/GOG Games/Baldur's Gate 2 >
Type setup-bgt.exe and hit enter, this will begin the patching process. Follow the onscreen instructions (just asks a few simple mostly Y or N questions) and let it do it's thing. Get yourself a sammich or something as this takes a few minutes.
Step 6. In the Wineskin wrapper, point the EXE launcher to BGMain.exe found in your BG2 folder (should be found in C:/GOG Games/Baldur's Gate 2/BGMain.exe). VOILA!! You're golden!! Do note that this will basically allow you to play from the start of BG1 to the conclusion of BG2 using the graphically-superior BG2 engine. There's even a scripted event separating the two games so you'll know when you're moving into BG2. Have fun!!
Post edited April 30, 2014 by famouswolfe