http://bmwfans.info/parts/catalog/E85/Roadster/Europe/Z4_M3.2-S54/RHD/N/2006/june/browse/seats/sports_seat_upholstery_parts/
Has anyone tried this? Not sure I've seen if so.
You'll need (6) from that list, says about $80. Then switches.. I assume if you've got electric heated you'll have the right loom already.