I don't know exactly to what extent you mean to modify a tub for handicapp. I'm a 25 year Mser (muliple sclerois) and today take showers using a tub seat that I find to be very safe and was not a lot of money $135.00. Prior to a seat I had hand rail installed that offer alot of support and security that lmost an handiman could install. I might suggestbefore doing anything install something o the base of tub to avoid sliding. Iff you'd like send me your emailI send you pictures of what We have done.