I installed Steam and everything that comes with that CrossTie along with my disc version of this game and Mono, but when I attempt to run the launcher, it seems to have some kind of error with DirectX trying to load native code in Mono that Mono can't handle. Oh well. I guess I'll stick to BootCamp for this one.
It didn't try to install .NET 3.5 though I suspect that was imminent, supposing it could first get past this.
This is the command output:
Method '<Module>:Direct3DCreate9 (uint)' in assembly 'C:\windows\assembly\GAC\Microsoft.DirectX.Direct3D\1.0.2902.0__31bf3856ad364e35\Microsoft.DirectX.Direct3D.dll' contains native code that cannot be executed by Mono in modules loaded from byte arrays. The assembly was probably created using C++/CLI.