I believe, based on a few posts I have seen, that dusting rodents with some sort of vitamin powder is something that has been done by at least some keepers in the past.

As Robin (rabernet) pointed out, no one has studied the nutritional requirements of BPs, so no one knows for sure what they need. However, they appear to do quite well on rodents without any additional supplements. That is what they eat in the wild afterall. It is possible, even probable, that the rodents they eat in the wild have a different nutritional makeup than the captive mice & rats that we feed them. However, if you added more calcium, for example, you wouldn't know if you were making it better, or overdosing them on something they are already getting more than they need.

I think the reason supplements are more widely used for various lizards is because lizards, as a general rule, have a move varied diet in the wild than snakes do.