Year's back I got tired of pouring lube all over myself while trying to top-off the leaky XFER & XMSN before an "exercise" ride. At NAPA I bought a little pump that fit on NAPA's one gallon jug of gear lube. (Or, maybe it was all one deal with the gallon of lube.) The end of the hose has a little plastic clip that holds it in place in the filler hole while you're pumping. The hose is clear so you can see the lube is flowing.
It's time consuming for a complete oil change, though. I've never measured the volume of lube that squirts out per pump, but for topping-off its fine. I've thought about making something from an empty metal one gallon can (paint thinner, kerosene, etc) that would take air from the compressor (regulated to X? psi) to force flow lube out through a tube. It's still just a mental design.
