Wouldn't it be easier to do voiceovers and recording seperately?
EDIT: I'd be happy to record a voiceover, but I don't know if I could actually remember to visit a server at the correct time.
I only have a cheapo mic, but my dad teaches radio journalism, so I should be able to get hold of some decent kit if it won't be good enough.
A greater problem at the moment is that I have sound problems on my computer (I don't know if this will affect recording, but I haven't tried yet).
Also I forsee a problem, you can see the mouth of the default model (without helmet) so it would look really dumb, and equally so if everyone wore a helmet.