Take UN-lubed patch (if you mess this up, I promise you'll only do it once! lol), put it in your mouth. Work spit into it while measuring and dumping the main charge. Once the charge is in the barrel, remove patch from mouth (make sure there's no grains of powder on the fingers going for the patch! lol), and load it under a round ball.
Works pretty well, but you will wind up spitting out patch fibers from time to time. Don't inhale the patch, either, obviously.
The other option, recommended to me by a member here, is to use Hoppes 9+. I've found this to be less messy, easier to load, and accurate. Great for range sessions where using a fat-based lube is messy, using spit patches is tedious/irksome to spit out the patch fibers and such....the Hoppes 9+ route for me works much better.
It smells like good ol' Hoppes, but is more "foamy" when you shake it, and it's super slick. I put a patch over the mouth of the bottle, thumb over the patch, give it a shake or two, then remove the patch from the bottle and use my fingers to make sure it gets all over the patch. The Hoppes will evaporate off your fingers fairly quickly with no residue, which means you're not a greasy messy by the end of the range session. Always a plus!