How To Convert A Lever-Style Bathtub Drain To A Lift-And-Turn Style

I've got a bathtub drain that is just that - a drain. You'd put a rubber stopper in it if you wanted to fill the tub with water. Reading all the articles on the Internet, it sounds like no one has ever heard of such a drain. They all talk about drains with some type of built-in stopper - either lever operated or some form of pop-up. I want to replace my drain with one with a foot-operated pop-up stopper. Can this be done without getting under the tub?

In order to remove the old stopper, insert the handles of a pair of pliers into the drain and turn them against the crossbars to loosen the stopper. We actually used two pliers.. one in the stopper and one to turn the plier handles! It took several tries to get the new stopper to seat correctly.We had to substitute a different rubber seal than the one in our repair kit because it was too small and the old one was too big.