They're really simple to fit mate, i did mine a few weeks ago, beware though they are alot heavier than the standard seats and the build quality is solid, regarding wiring them up this is a peice of cake too
I wired them into the cig lighter, easy to remove, open ashtray fully and undo the screw that holds it in, pull it out and splice into the 2 wires, make sure you feed the wire for the seats along the same route as the existing cig lighter wire or else the ashtray wont fit back in
like i found out lol
undo the 2 screws that fasten the centre console in place and remove the little plastic cover under the handbrake and feed the remaining wire under the carpet and bobs your uncle, might just add that you will have to remove your existing seats in order to get the wire under the carpet,
finally i just connected the seats to the new "loom" using bullet connectors.
oops nearly forgot to mention that the airbag connectors ARE different and will not connect together, the airbag wires are blue black and brown and the car wires arebrown blue and white/green iirc. all i did was to chop the connectors from my original seats and join them to the S3 seats, same colour wires so you cant go wrong then just simply plug them in.
or you could go to audi and purchase some connector blocks, go armed with a registration plate from a mk1 S3 though
it would also be a wise idea to test that all the electrics work prior to fitting though...
hope this helps.