You can't automatically avoid all of MFC, but you can provide a list of classes or functions to avoid (like CString). Here's the registry section: (The 10.0 is for VS2010. It will be different for earlier versions of Visual Studio)
HKEY_LOCAL_MACHINE\SOFTWAR
E\Microsof
t\VisualSt
udio\10.0\
NativeDE\S
tepOver
More information can be found at:
http://stackoverflow.com/questions/626744/is-there-a-way-to-automatically-avoiding-stepping-into-certain-functions-in-visua