All I did was go into preferences > plugins > check the box for additional plugins > and navigated to the Topaz root folder and hit ok and save. This was the tech advice from Topaz and currently the only option I know of.
Worked like a charm on Windows 7 Ultimate, both 64 and 32 bit versions of CS6. The drag is it appears one cannot choose more than one folder so if the rest of your plugins don't install on their own (a couple of mine didn't, fortunately I don't use them much) then your left using CS5 for those.
I think I read somewhere here that Jeff Schewe stated Adobe changed something in the way it handled plugins, what or why I do not know.
I hope this helps,
Phil