If V-Vocal is the way you have chosen, just copy the original track and start experimenting. Add minor pitch and timing changes, and play with formant (I don't remember, if VV has formant setting, though). I don't think there's a tutorial for this (??). Allthough multiple, slightly different takes of the backing vocals would make your work a little easier. You will not be able to make a convincing female voice out of a daddy-male voice, and with the male variations you'll have to settle with quite a few compromises. At least, don't expect to get something publishable.
With Melodyne you'd propably get better results, but, IMO, for somewhat convincing results you'd need at least three different voices to start with, one of them female.