if its anything like this rheostat http://www.reptilesupply.com/images/...tat_deluxe.jpg i'd advise against it.
rheterostats are only good if you have a steady constant temperature in the surrounding room(s). thermostats are MUCH more foolproof (assuming you have a good one). i think there are a lot of threads explaining the differences and the goods and bads.
note: i looked up a rheostat and i still have no idea what it is. im not every electrical-savvy.
that said, your baby looks adorable and he is so pretty. his enclosure looks awesome and very natural i hope he's good for you!