Thanks. I tried, and tried and tried and it was still a no go. For some reason, the dotnet45 entry in winetricks bundled with Wineskin on OS X seems to go all wonky; it installed .NET 2, then halted and asked to download the installer for .NET 3, and then halted because it said that it didn't need to install .NET 4.5 because .NET 2 was already present. When I ran msxml3 first, it also didn't want to install .NET 4.5.
Two things that I remember I did at some point, but I have no idea if they affect you too:
1) I had to get rid of the old (ubuntu) wine and also removed wine-mono, because it ships a "sort of .NET" library that just makes installing the real .NET troublesome.
2) I also got stuck on installing .NET 3. The reason was that the installation was complete, but it was minimized in the system tray. If you cancel the installation at that point (by terminating winetricks), you will stop the process and you will make it impossible to install .NET 4.5.
What I had to do instead is (after a refresh of the .wine directory) to right-click on the system tray on the .NET install icon, and select "Finish installation" (or something to that effect) without terminating winetricks. After that, winetricks continued and installed .NET 4.0 and .NET 4.5 one by one.
dotnet4 did work in Wintricks though, and after installing everything I still get the error message.
I understand. After installing everything "the right way", I got the "No suitable graphics card found error" in my setup and I solved it by removing stock Ubuntu Wine and installing the WineHQ version. I understand your problem may be unrelated.
PS: I also spent quite a bit of time setting this up, don't be discouraged!