The best way to get comfortable with a bike 'moving around' under you is to do some off road riding. You have no choice but to ride round with no grip and with the front and back tyres constantly letting go. It doesn't translate as being able to slide a bike on tarmac (not to mere mortals anyway), but if the tyre does lose traction for whatever reason, you've programmed yourself not to panic and do the wrong thing. On the dirt, you're generally taught to gas it if it's all going wrong, which goes against all your instincts!
It certainly helped my confidence on a bike in the wet and if, for whatever reason, it has a little step out, it's not the end of the world. I've still managed to highside a bike in the dry and low side one in the wet....there's no helping some people though
