From what I've read about N64 Roms and injecting, the answer is 'maybe'.
Getting an N64 emulator to run on the Wii is pretty difficult. Different games almost require different emulators. In one emulator Mario 64 will run like crap, in another, it runs great.
Even Nintendo has had problems making a working n64 emulator. They have to make a new one with tweaked settings for almost every virtual console game they release.
The virtual console emulator running Mario 64 is different from the one running Sin and Punishment.
Heres an article I found and read a week or so ago about it with some instructions on how to go about injecting Roms.
http://sieghai.wordpress.com/2008/05/17/ho...eases-tutorial/
Basically from the jist of it, it will come down to trying to inject your specific ROM into various n64 WADs till you find one that runs it smoothly. I've heard the emulator for Sin and Punishment is the best one to try first.
I haven't tried it myself yet(We just got our Wii for christmas and I'm still actual Wii games and don't have a desire to play any N64 games just yet).
Good luck if you try it out.