Can I specify whether to start a new process as a 32-bit or 64-bit process dynamically?

I have a boatload of test console applications that are built as AnyCPU.  These apps test several class libraries that are also built as AnyCPU.  I need to make sure that the class libraries will run in 64-bit processes, 32-bit processes on 64-bit Windows, and 32-bit processes on 32-bit windows, so... I need to start the test console apps in both 64-bit and 32-bit processes on 64-bit Windows (from C#).  I expected to see something in Process or ProcessStartInfo that would enable me to do this, but no-go.  Any ideas?  I don't like the idea of creating wrappers for each class - if I have to do that, I'd just as soon abandon AnyCPU and go with x86 and x64 builds.