I've used mineral oil to treat mites in the past. As Rat160 said, just put a small amount on my hands and let the snake run through them until he's well coated. The mineral oil will suffocate any mites still on him, so as long as you clean his enclosure well before returning him to it, he should be fine. (I've also heard of this done with olive oil or baby oil with similar effects.) I always keep a close eye on the snake during his next shed, because it can sometimes be patchy as a result of the treatment, but that's easy enough to handle as long as you're watching for it.