man, i found this website that told exactly how to find a escaped snake. maybe i can dig it up.
i can tell you some stuff i member from it. make a sent trail with a p/k gerbil(in your case a small maybe pinkie or weanling gerbil) in the room you think he is in and make the sent trail to lead to a warm cardboard box with a circular hole cut into it. hopefully in the morning he'll be in the box.
and you can try putting crumpled up newspaper behind a bookshelf etc., anything that they would crawl along and in the middle of the night sit and wait with all the lights turned off and everything is quiet with a flash light in hand(leave it turned off until you hear the newspaper crackle) then go get him.
i cant member anything else but hopefully that helps.