Drill and tap the muffler for a fuel nipple, then drill and tap the crankcase in a handy spot for another. Then connect the two with a piece of fuel tubing. The impulses from the exhaust (not the actual exhaust) would be fed into the tubing, and maybe with a check valve of some kind, the negative (scavenging) impulses could siphon off a little pressure out of the crankcase. Similar to how us glow guys pressurize fuel tanks, but kind of in reverse. I dunno, sounded interesting. Easy enough to cap off if it doesn't work.