Yea, slantsix.org has this fully covered. Here's the best page on that site.

http://slantsix.org/forum/viewtopic.php?t=15779

I made the unit below for my 73 Dart. It was wired like explained on slantsix including the relay. Notice the heatsink underneith and the electic grease under the module. Important stuff. Some guys just bolt the module to the inner fender to act as a heatsink, but I burned a few that way. This heatsink was adopted from a computer CPU heatsink.

Worked great, if a little ugly (that can be fixed), and I've always copied it in every Mopar I've owned since.