At this point, you shouldn't worry too much about fermentation character from the yeast that you add. The big thing is to make sure that the finishing yeast matches Bell's in relative dryness. If Bell's a a dry finishing IPA, WLP001/1056 is your yeast, if it's more medium-dry, then use a slightly sweeter yeast, such as East Coast Ale. (I don't know Bell's well out here in the west.) Make a starter with that yeast and pitch it into your beer when it is actively fermenting the starter (about 8-12 hours) for best results. But before you bother, taste the beer. There's a good chance that other fermentation flaws in the beer are serious and the beer isn't worth keeping. (Sorry. It's happened to me more than once too.) Of course, it would cost about $8 to try to fix the beer and cross your fingers, so don't toss it too hastily.
As far as what went wrong, the most likely problem is yeast health, which is actually more important than cell count according to White Lab's Chris White. (White is insistent that you should get everything right for optimal beer, but he says yeast health is the number one thing that produces bad beer, with cell count, low oxygen, and temperature being close behind.) Yeast that has bottle conditioned a beer is living in it's own piss and probably also a few months old. To successfully use such yeast without laboratory techniques, you need to make a very small starter (100mL) with a low gravity, like 1.030, and add the yeast from one six pack. Then pitch that into a slightly larger (like 500 mL) of similar starter, then pitch that into a 1000 mL starter. That will get you something like 75 billion cells, slightly less than a yeast pack. You then use that in a starter as you would normally for the yeast style you're using.
Good luck.
