I've tried an in shower one before and it made the bath extremely slippy to to point I had to stop using it as I'm not exactly the steadiest person at the best of times and was an accident waiting to happen. That was years ago, and maybe they've improved, or I tried a particularly slippy one (Nivea one I think it was) but I'm not risking it.
I've got a Vaseline spray moisturiser, bit like a deodorant can spray wise) but it goes on quite watery so ideally needs rubbing it in. I got it more for my legs after shaving them, and tried spraying it while sat on my bath board so it only drips in the bath (again potentially slippy, but easier to wash out if you swing your legs out after, rather than standing in the bath ) but I wasn't very impressed. Needed a lot of spray though for not a very big area, and it didn't seem like the tin would last very long.
Is there a particular area you're focussing on? Do you have a bath you can get it? There are things that could be put in the bath water to help moisturise the skin over a larger area, if that's a possibility.