My wife received most of her childhood enemas in a bathroom. Here is how:
Her mother summoned her to the bathroom. If at home, this was most often not the main bathroom, shared with siblings and visitors, but the parents' ensuite bathroom. She was told to disrobe, which meant removing skirt/dress/trousers and panties, so she would generally end up wearing a T-shirt and socks. (One of her worst enemas recollections was when she was made to disrobe completely, since her clothes were soiled by vomit.)
Sometimes the enema bag was already ready, sometimes her mom would prepare it while she disrobed. For stomach aches, her mom generally added bicarbonate of soda to water at body temperature (maybe she did not add the bicarbonate in case of mere constipation, she's now unsure). The bag was completely filled, and hung from a towel rack.
She then had to assume the position: kneeling on the floor, knees somewhat apart, head hown, bottom up. Her mom would smear Vaseline on the nozzle, and often smear the excess vaseline on her finger onto her anus. Then, she would warn about incoming insertion and insert the nozzle. She would then open the clamp.
Her mother held the nozzle in, kneeling behind the patient, throughout injection.
The towel rack was not high and the pressure and flow were thus not too high. If the patient mentioned discomfort, the mother would stop the flow for a moment. If discomfort was too strong, the mother would stop the enema altogether.
There was little or no waiting after the enema was given before going potty. My wife generally waited, still in position, until mom was out of the room, so as to expel the enema in private. Sometimes, however, she started to expel in front of her mother; and she also recalls her mother returning to the bathroom to refill the bag for a second enema while she was still on the toilet.
Her mother sometimes asked her not to flush so that she could inspect the results.
An enema could be stopped if too uncomfortable. However, if stopped too early (her mother was the judge), a second enema was given, the bag being refilled in between. On at least one occasion, she got three enemas in a row.
Her mother found enemas in the bathroom quite convenient: little worry about leaks, patient close to the toilet. However, as my wife got older, she realized the position gave her mother a close-up view of her anus and genitals throughout the injection, which embarrassed her.