All I can say is DON'T worry! If you watch your fat intake, which I have found surprisingly easy to do, you won't have symptoms, other than odd looking poo.
I only had one episode, and really think it was from the sugarfree/fat free ice cream I ate, I tend to be lactose intolerant. (the less fat a dairy product contains the more lactose it has) And even that wasn't some horror story of uncontrollable mess.
Definitely do the "prediet pill" thing, low fat diet a few days before you start taking the pills.