OK- I received an excellent answer from Steve in Outlaw tech support. He spoke with REL and the hookup would be as follows:

Red hi-level wire from REL to + amp terminal used for Right Front channel
Yellow hi-level wire from REL to + amp terminal used for Left Front channel
Black hi-level wire from REL to chassis ground terminal on 770.

If anyone else comes across this problem, the answer has been posted.
Thanks Outlaw and thanks Steve for going out of your way to help me out!