The only thing I know of to prevent bile diarrhea on your own is an exremely low fat diet. That got rid of my D after I got my GB out--although it also caused me to have severe C, so it was a no-win situation.
I had three hidascans and an ultrasound over the course of 5 years before I got a reading that would allow me to have it taken out. It was clearly my problem as I have never hurt and been sick again like I used to be when I had my gall bladder in. I still have bile D, but I take Welchol and that helps a lot.
Even if you still have your GB, you can take the Welchol, provided it doens't mess up your other meds (it can keep you from absorbing certain ones). Some people with IBS have GBs that seem to be fine, but they still have the bile problem; probably because their intestines are emptying so quickly they don't have time to absorb the bile properly. And these people take Welchol to some relief. So see if you can get your GI to give you some of that and see if it helps.
Also, probiotics and calcium. Both of these have helped me in the past when my guts were tore up for some reason other than bile. Also, bile, being an acid, can irritate your intestines, and calcium can help soothe irritations, so it's good to take the calcium when you're having bile anyways. If it also helps dry you up, so much the better.
Unfortunately, it may take them a while to discover it's you GB. Doctors, for some reason, tend to think you can only have one thing wrong with you at a time, so once they diagnose you with a problem (Crohn's) they think you'll never have any other GI problem (bad GB, Celiac's). I do usually tell people if they are certainly they have a bad GB, then the night or two before they get a hidascan, to eat everything they know will make them sick to try and induce a gall bladder attack and inflame/aggrevate it enough that it will show up. I think that's why mine didn't show up the first two times; it was in a period of remission and was functioning decently.