Try using a syringe with the plastic tip cut off to squirt some KY up into his sheath. Longe him for a while to really "stir things up" in there, then flush with warm water. A tack-cleaning sponge held between the fingers might also work.
The inherent vice of Capitalism is the unequal sharing of blessings. The inherent virtue of Socialism is the equal sharing of miseries. Winston Churchill
Oh, it's a challenge! I have 2 minis and not terribly big hands but there was definitely some squirming involved, especially from the older one who tries to kick. Do the best you can and use the KY stuff.
I opened this thread not because I had any words of wisdom to offer the OP, but because I knew, just KNEW that fellow COTHers would exhibit their sharp wit and humor at this poor mini's expense. I was not disappointed. LOVE the stick art!