I repaired a row of urchin punctures with a 2-part PVC glue (like used for inflatable boats) and a vinyl patch. It's held for 5 years or more, and I'm about to patch another pinhole leak. The BC bladder is made of laminated fabric like many BCs - the fabric is one-piece w/nylon exterior - like a fabric air mattress). If it's a pvc bladder inside a cordura nylon or other separate nylon casing, like many wings I think, it should be a similar fix (take out the bladder to repair). Sandwich the patch between two blocks with a vise or clamp to get good pressure on it, if you can.
I've had good luck fixing pinhole leaks in my hypalon boat with Zap glue and the accelerant that goes with it (basically, super-glue). I haven't tried that with a BC, but I'm thinking about that as the first effort with the new pinhole.
Another thing that might work, if it doesn't look easy to get a patch mated up, is fix-a-flat. Haven't tried it, but it might work. There's a similar product sold for inflatable boats.