The tips mom and ipoop gave were my best chance of surviving the discomfort. With all of the tricks in the book, you will still have discomfort if you're inflamed. I have had inflammation so bad that I couldn't retain a suppository. A suppository is considerably easier to retain. If I can't retain that, what is the likelihood that I would be able to retain a 4g enema? So, I would do the following, either use cortifoam (much less to retain) or use half the 4g enema, expel it if I couldn't retain it, use the other half - sometimes + a supp.
The other thing is deep breathing. Lay down on your left side and breath deep. Be aware it's going to pass if you can survive the minute or two of discomfort. If all else fails, do the things I said above; half, supp, foam