First off, have you used the search function? That would give you loads of answers.
But here are some methods you can try anyway:
Put some paper bags all round the edges of the room, turn all the lights off (do it at night as snakes are nocturnal) and sit in silence. If your snake is moving round the room, you'll be able to hear him sliding over the bags.
You can try putting some flour in front of every doorway. Then, if the snake slithers through a door, he'll leave a trail you can follow.
Pop-bottle traps, if he's a small snake. Pop a pinkie inside an empty clean pop bottle and invert the top so once the snake has eaten the pinkie he can't get out again due to the lump in his belly. You can carefully cut the bottle to free the snake.
And if you haven't already I would put the mouse lure and heat source on the edges of the room. Snakes tend to move round the walls for a sense of security.
Other than that, just keep searching. Check under and in everything, even if you can't see how the snake could be there. They are GREAT at getting in to odd places. And don't forget, he could have left the room by now, although he probably hasn't gone too far.
Good luck in the search!
