Hinduism is a bit different, in that yes there are multiple deities (polytheism), but they also tend to see all of those deities as but manifestations of over arching God, so in essence it can be termed monotheistic as well.
I suppose you could follow the traditions without actually believing in the religious ideas behind them. Just go through the motions; like some "followers" of other religions often do. There's nothing wrong with it, as long as you don't pretend a belief you don't feel.
Hindus are polytheistic BUT in a sense they believe all gods are parts of the same one god...so if you just pray to the one god, it should be fine. however i do not the name of their all-god or however you want to refer to him.