I have my version of a "Shower Shot" which does not use the metal tip or shower stall. Let me explain! Some years ago I installed a lever operated ball valve between the shower main line and the shower head to controll the pressure/flow to the shower head. With this valve in line, I do not need to change the hot and cold mix for the correct temperature since it remains unchanged from shower to shower. However, as before, I do run the water to allow it to come to temperature. I use the temperature for showers or open tube colonics. For my colonics, I unscrew the hand held shower head and screw in a 1/2 in. male NPT adapter. The adapter then has a 3/8 inch barb on the output end to accept 5/16 hose.
The hose I use is clear vinyl and ten feet long. The slight variation between the O.D. of the barb and the I.D. of thevinyl works well for me. I simply warm up the end and expand it by inserting a pair of needle nose pliars into the warm tube and pulling the handles apart. That opens the jaws of the pliars and expands the tube to slip easily over the barb. The expanded tube is too large to hold water. Beauty of this plastic is that it shrinks when it is heated. So... slip the exanded end over the barb and warm it up an watch it contract to fit the contour of the barb for a water tight joint.
Now, turn your attention to the business end of the plastic hose. If I am using a commercial nozzle such as a shower shot, simply slip it onto the hose, lubricate it slip it in and open the ball valve to the the desirred flow. This is an open tube colonic because water is flowing in and out of the colon at all times during the proceedure. Nature takes her course from here! I sit on the toilet and take fill after fill of warm, relaxing water interspursed by discharges of waste water.
For my last comment, I seldom use my Shower Shot but prefer my 48" colon tube for open tube irrigations or enemas. If there is a difference in the diameter of colon tube and the delivery tube, another adapter or reducer may again be required or simply expand the larger tube end to fit over the other. Most recently, I have been experimenting with a gate valve for that adaptation and have better flow control from the toilet seat. Whatever way you irrigate your colon, enjoy it because an enema a day keeps the doctor away.