i did some reading on it a while back.. and found a forum where there was a description.. cant find it to save my life right now... but my advice would to post on ls1tech.com and im sure someone will chime in (edit... it was the UDX ... not sure it applies.... and the interface was for canbus/BS3)
but try and post here aswell:
http://www.racepak.com/forums/viewforum.php?f=4
if i recall correctly the wiring part sounded really easy, and then it took some pain in the butt programming in the menus in the racepak...