Her VNC trial period has finished and for some reason the boss doesnt want to buy the software
Rant #2 today -- Man I hate these cheap lazy bosses. Tell him you won't do anything illegal for the company. If you get fired for THAT, then you can start some real fun.

That aside, I've worked with VNC for a long time --

1) At my previous company, we installed VNC Free Edition on all user computers. Again, we're back to companies being cheap, because that DEFINITELY is not in accordance with their license policies. But, alas, it worked just fine.
2) You should be able to clean the registry by hand if need be. Granted I haven't tried it for VNC, but I wouldn't expect it to be that hard to find all the keys associated with it.

But again, don't let him push you into breaking trial or license agreement. Business ethics should never be compromised.