As the old joke goes, "It wouldn't hurt." Otherwise there isn't any theraputic reason to do a coffee enema over a salt water enema. Once a week, taking the coffee solution slowly and continually massaging your abdomen to ease any cramping, should be okay.
A low residue diet is on that is low in bulk-forming foods -- low to no fiber content. It avoids overfilling the colon. You will have to experiment to find the ideal food mix to eat that prevents bloating yet allows for (more or less) normal bowel function. You doctor should have provided you with this information. If not go back and ask.