Bungee's bounce, not a good thing. While the 15-22 isn't that heavy to get up enough force to bust your lip I'd steer clear of bungees.

Blackhawk makes a copy of the VTAC LUSA sling mount BLACKHAWK! Rail Mount Sling Adapter - BLACKHAWK!and HD sling swivels BLACKHAWK! Heavy Duty Push Button Sling Swivel - BLACKHAWK!. They are nice pieces of kit although they do sit a bit proud.

Tactical Assault Gear makes a plastic hardware version of the VTAC sling for $15 shipped free. Padded Adjustable 2 Point Sling. I added a BLACKHAWK! Rapid Adjust 2 Point Sling - BLACKHAWK! to my 15-22 and really like it. Only drawback is the design limits how tight it can be made unlike the VTAC and TAG slings. It still does the job of getting the rifle out of the way though.