I tried installing 3.5, but got this .NET exception:
Code:
NullReferenceException
at f.m(ListView A_0)
at Diamond_TF3D_Config.frmMain.v(Object A_0, Event Args A_1)
...
I also tried the registry fix that was causing .NET exceptions for other people, but the fix wasn't needed for me (the DWORD value was already a DWORD).
I'm aware that I could edit the registry to accomplish what I need, but I'd rather not have to muck around in there if I don't really need to. Suppose if there's no easy way to do it without a helper app, then I'll contact the developer of the TF3D config app and report the bug.