I not so long ago changed my SE specrim for Nick's old M3 paddle shift equipped steering wheel.
Being an M3 wheel I've got tri-stitching and a nice thick leather rim
Plus Nick equipped it with the extended paddles as well. It's a great mod the left hand paddles does down shifts while the right hand side paddle takes care of the upshifts, seems strange that I'm explaining it this way but the reason behind the explanation is down to BMW adopting a push/pull setup on both the paddles on the standard SE rim. Strange that, but once used you'll be addicted.
On the slip ring question the new M3 wheel went straight on my SE took 20 odd mins to do.
Incidentally if anyone wants an SE rim let me know as I've still got my old one at the moment.