Yeah Eric I've seen and used what looks like this. It's in Freedom of the Hills and Duane Raleigh's Knots and Ropes for Climbers as the Carabiner Wrap. Works well for single or double (strands). I scanned a pic but it was crappy. Anyways, yeag you just wrap 2-4 wraps of rope along the solid spine of a locking crab (biner), starting at the top (anchor end) and it gives plenty of twisty friction. Good sugestion Eric! I'd forgotten this one.
quem deus perdere vult, primus dementat