This is a re-posting, but one that seems right in the wheelhouse of your question.
This is rough but quick and effective:
It is for experienced enema takers only!
If you haven't taken enemas before this is nothing to mess with!!
When you are doing the liquid diet the day before: Drink ONE bottle of either Gatorade or Powerade in the 32 oz bottle.
Wash the bottle out repeatedly until you can no longer smell the original content and let it dry.
Pour in 18 oz of GLYCERIN.
Unscrew the cap from ONE Fleet enema and pour that in.
Fill the rest of the bottle with hot water and shake well. Then set it aside and let the water and glycerin mix.
Right before bed, shake it well again.
Day of the cleanout
Whatever you do, DO NOT EAT!!
Drink plenty of water.
Place the Powerade bottle in a sink or dishpan full of hot water
Set up the enema bed as you would for a Simms position (Left side position) enema. Within arm's reach you will need two clean washcloths. One that can be a good bite rag and the other to stuff in your butt crack if you start to leak on the way to the toilet.
I keep a small dishpan where I can just slide it out, hand my head over the edge of the bed just in case anything DOES come out.
I have used a rather small o[pen-top bag, but I don't think an open-top is really needed. It is preferred!
Use a nozzle that you hare familiar and comfortable with.
Make sure to take a pee before getting in position.
When you pour the solution in the bag, you are going to have to be careful of the hose, because most clamps that can hold back water will seep with this mixture.
You might want to transfer it to the bag at the last possible minute.
Get a good, relaxed position. Do the insertion as you normally would.
When it comes time to open the valve, remember this mixture will inject FAST!
Your retention time will be SHORT compared to what you are used to. I hold most types of enemas 15 minutes. While I have used this a total of 3 times in my life, and all three times told myself “Never again” I have yet to make it past 9 minutes on this mixture.
Like any enema, try to hold it until you are at the point of just enough time from spontaneous expulsion to make it to the toilet.
Once on the toilet, expect THE ENTIRE CONTENTS of your bowels to be out in a couple of minutes!
You will need no other laxatives or enemas for at least several days!
Be prepared in case it DOES come out both ends at once! That happened one out of the three times in my life that I have used this mixture. It was just gastric juices, no food scraps!
You will need a couple of hours for everything to settle down, You can eat once it has settled down. nothing too physically strenuous the rest of the day and no girdle the rest of the day.