I've grown in a rubber maid tub before, so it's not impossible. It's a pain in the arse to mount the lights, and computer fans, especially if you don't want to drill any holes, to keep the tub looking normal.
I'm not sure if it's better to top or not, I've never really played with that, but you're definitely going to have to tie the ladies down. Maybe start by tying the plant down, shaping it around the contour of your pot, as it grows. The key to LST is to be gentle, and go slow (develop the shape slowly, AS it grows).
Some lst threadS:
http://www.marijuanapassion.com/forum/showthread.php?p=147230&posted=1#post147230
http://www.marijuanapassion.com/forum/showthread.php?t=8886
http://www.marijuanapassion.com/forum/showthread.php?t=2715&highlight=training
I have never flowered in a tub, but it's possible, just have to have enough grow room. How big is your tub anyways?
I can forsee you having problems with smell.. Unless you have some type of air-cleaning device, or home-made carbon filter, your tub is going to stink up your place (and your clothes, if it's in the closet), when it's put into flowering. It may not be as obvious to you though, because you'll be living with the stinky thing, and your nostrils will 'ignore' the smell after a while.
What kind of people go through your closet, when they're over, anyways?