So its a tub, with just a faucet to fill it, but not diverter or shower outlet above?
If so, im pretty sure you will have to remove the 'spout' part and replace that spout with a new spout that has a diverter and provisions for the hose built in. Id get a plumber to make the swap only because I assume this home must be 80's vintage or older and it might not 'disassemble' as cleanly as you would like. Should be an easy swap out though.
[This message has been edited by BrazosDog02 (edited 5/6/2013 1:42p).]