Well... I'd want to record the best possible one and then add any effects later.. you can compress (which is done to all vocals), and add any other effects you want then ..
I'm using ProTools, and I've been doing some research the last few days into plug ins...
I found the one I think I'll need to use , just have to download the demo version and take it to school (since Protools is primarily a Mac program) where I have the proper equipment to make use of it.
I had a great idea in class yesterday also... we had to record a choir of 35 10-12 year old girls that were singing patriotic songs, that were going to be played today at some sort of tribute. The songs they were singing to were designed for adult voices and in a different key. So, in the studio we have a nice piece of equipment called a harmonizer, and it can take any peice of audio and take it up a few keys, making it sound higher pitched. We put the songs through that , and made the background vocals sound like the chipmunks or something ;D So I bet that I could put some vocal stuff through that.. make it a higher key, add some effects, and well... see what I get.. LOL ;D
I'll keep you all up to date.. and as far as the specifics of adding the voices to the game, file format, etc.. you'll have to ask LCD when he gets back from vacation. I'm pretty sure that he's got that one just about figured out. Adding the voice to the game is what I think he had in mind too.. so you can choose it like you can your face or glasses under the options