Nice tag! Glad you grabbed the camera, it's always the first thing I think of after getting bitten too.
As far as getting the snake off.. it can be a little difficult especially if it's your hand that smells like the rat. I've always been able to get them to let go just by holding the snake behind the head.. it takes a few moments (during that time, sometimes they crush down a little.. ouch!) but they've always let go. Once I had to drag the snake out of the room (she's over 7') as she was latched onto my hand, the movement and getting away from the rat smell was all it took. Then try their head in water or using the alcohol as mentioned, just try to be careful not to actually pour the liquid down the glottis.
