From my understanding Visual Studio 2005 always uses MFC8 automaticly, VS2008 MFC9 and VS2010 the MFC10.
Can use a newer Visual Studio Version and still link to an older MFC Version?
I searched the options and the project settings all over but I could not find any option about the MFC.
VS2010 apparently (I don't have it, so I haven't tried it) has the ability to use both VS2008 and VS2010 toolsets to build the applications, provided they are both installed in the machine.
More here
I would expect Visual Studio 11 to have the same ability, but who knows...