I would have to say the most important (and nonspecialized) positions would be the voice actors. Yes, we could really use a UI/portrait artist or an installer coder, but we have practically nothing to work with for some of these civs' voices.
ANYONE with a suitable voice and decent acting skills can do this. We may have to work with you a bit to get an accent down if you aren't a specific nationality, but it really doesn't take as much dedication as the other positions.
Also, don't forget that it doesn't have to be YOUR voice...it can be your friend's, your dad's, your neighbor's, etc, etc. Just as long as that person is interested and willing to work with us, that would be great. Please consider this position even if you are not a modder in any way. There is no reason for you to be.
The most demanding position would probably be the graphic designer. Although, for the avatars, we're looking for more of a plain artist who can scan their drawings. If you are a good artist for unit portraits, I suppose I could Photoshop your units into color if you're not also experienced with graphic design.