How do I install a bathtub drain over a floor joist.?

I am remodeling the bathroom and the drain for the new bathtub sits right over a floor joist. How do I go about getting the pipe in the proper position? The bathroom is fairly small (7'x8'), so we really do not have any option to move the tub. The joists are 2"x10". Is it ok to remove some of the top of the joist if the bottom 2/3rds is reinforced withplywood or like material? Any suggestions??