Iv managed to make the NPC's speak, but like it or not, you have to record a voice for them and then get the lip sync done. I recorded some voices myself and it didn't turn out bad, although now, for my first major mod, I'm using silent files because there is just too much dialog in different voices.
If however you only have one or two NPC's to voice, just record the dialog yourself. This is the page I used when I did it myself: http://cs.elderscrolls.com/constwiki/index.php/Dialogue_Tutorial
Hope that helps
MVK
BTW: I think that http://www.invision.tesalliance.org/forums/index.php?/index?quot; have a voice actors section - perhaps you could look there for more information.