I paint the occasional leather jacket, and a technique that works well for me is ironing. just cover the piece with tissue paper and iron it on high for 10 or 15 min. this "melts" acrylic paint into the leather. It's an old airbrushers trick.
Try this guy, A lot of guys on the Hardknock forum deal with him.
http://cgi.ebay.com/ebaymotors/Custom-seat-pan-Chopper-WCC-solo-harley-knucklehead-NC_W0QQitemZ350290929949QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item518ef7691d