Its easy, but sometimes the bolts at either end are hard to line up with the threads. Best thing to do is have some quick clamps handy to move things together or spread them apart.
------ Follow up post added March 30th, 2010 04:58 AM ------
Oh, I'm dumb, you mean the one under the tub - ug, that's not easy at all. The good news is that when you buy the parts as a retrofit kit instead of factory-fitted, they come split, so you could easily saw the middle and then sleeve and bolt the bar on reinstall.