I have bought a pair of race seats (see below). They are made of kevlar, but are finished in gelcoat. I'd like to improve the cosmetics by skinning the gelcoat in carbon. Not the whole seat, as I'll have a seat insert made to fill the middle like this. I just want to skin the top and 

yes... A worthwhile project..

file or sand a small area of the seat, and notice the smell ... is it polyester? (will smell of styrene) then make sure that the smell is quite weak, if it is strong, using epoxy to skin it with may give you problems.

Practice on a few smaller parts, first a relatively flat part, then one with more complex compound curves like in the seat.

I have no personal experience with skinning polyester parts, other than one very old fibreglass case, which worked out very well.

You may meed some sort of method of holding the CF in place, vacuum bagging it would be the easiest way, but I've seen polythene bags with warm water or dry sand used to good effect.

The few parts I've skinned were done with peelply on top of the CF and then clear-coated with 2-comp sprayed on.

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Epoxy bonds to polyester fine, just need to make sure the surface prep is good.