In reply to Paul- backhouse:
Hey, it's quite dependent on the details, but your best bet might be to get in touch with Maureen (Mo) Beck (a one-handed climber) who last I heard was working for Paradox Sports:
mbeck@paradoxsports.org
In fact, check out the paradox website too. She advises against using a gri-gri (too hard to pay out slack/lower), and goes with an ATC guide/Reverso, so presumably has worked out a method for making it safe.
Hope that helps!
