Here is what I have done: I have purchased a shower kit like the one listed below at ebay.
"Shower Shot Bidet Enema Douche Stainless Steel $44.95!
BUY IT NOW 2 Item number: 160243761427"
Then have gone to ACE HARDWARE store and at the plumbing supply department bought a valve with screw on's that will work with the hoses that come with the kit, but also have purchased a repair shower hose for a like item for the shower head to make the assembly longer and easier to use.
This allows you to first set the water temperature, and also to control the flow of the water from full on to off and everything in between.
Now you can have fun.
I have mine set up so that you can still use the shower head at the same time, that way you stay warm with the flow of the water over you, or my partner, have full control, and you can expel in the shower and it all goes down the drain.
Like to get my lady friends in the shower, give then an enema and perform oral sex at the same time, makes for alot of fun. Mike