The lemon drink you are talking about is not the B & P shakes.
The lemon drink consists of lemons, grade B maple syrup and cayenne pepper. If you go to the homepage and click on Lemonade Diet on the left hand side of the page, it will explain exactly what you need to do. You remain on this for 5-10 days or longer. You can continue taking the B & P shakes while doing the lemon drink. You would also try to include epsom salt, taken either by mouth or by an enema.
You sound pretty backed up. I feel for you. I bet once you start going, you won't quit.
But, since you have had bowel problems all your life, I would expect a Colon Cleanse to take you months and months. Just don't give up. You will be glad you hung in there.