Do a little peeking at the Bowel Cleanse and Fasting forums for some P&B info. P&B will clean all the old stuff hanging around the walls of your colon. It takes a while (weeks or more) usually, but is great to get that yuck out. For your purpose now, to do liver cleanse, just be sure your bowels are regular, that you get 1-3 BMs a day. Once you are at that point, OK to liver flush. Want to be sure you are regular so that you get the stones all the way through and not stuck. Stones are full of viruses and toxins; you want them GONE!
I can highly recommend Dr. Schultz's IF #1 for the purpose of being sure the bowels are regular. Just doing SWF (Salt-Water-Flush) in the mornings will help move things through too.