Some basic acts_as_authenticated questions

"script/generate authenticated user account" generates a User model
and an Account controller.

My question is, I already have a Person model. If I generate the
authentication hoodoo using Person instead of User, will this muck
things up?

Also, I'm assuming the acts as stuff would overwrite the code I have
in my current model. And it won't break anything, if I put that stuff
back in there?

(I have to ask these dumb questions, because I'm still figuring
subversion out and can't just try it...)