Clearing out your evacuation sites is REALLY important. Dead parasties clogged up in your system will cause additional problems.
If you are really constipated and have not had regular bowel movements for some time chances are you have alot of faecal matter along with dead parasites which really needs to be moved out for a successful cleanse to take place.
I do suggest colonic irrigation along with enema's to clear you out. Make sure the water is clean and sterilised. Alternatively you can use Oxypowder which will works quite well also. Make sure you are always well hydrated as Oxypowder is very dehydrated (learned from experience!)