I did a somewhat similar repair to the chainstays of a Reynolds 501 steel Peugeot sport bike 15 years ago. I picked up the frame "as is" after it was hit hard by probably an SUV from the side. Trashed fork, dented top tube and both chainstays about to break behind the support. (Cracks totaled a full circumference.)
I built and raced sailboats in a former life and happened to have a few feet of unidirectional CF as well as Gougeon Bros. boatbuilding epoxy and years of wet laminating skills. I stripped the paint from above and forward of the BB shell back to several inches behind the chainstay support. Took the CF and cut it to several narrow strips. Masked off the tubes beyond the paint stripping. Taped the ends of the fiberglass strips firmly to the painted portions of the seat and down tubes.
Then I mixed the epoxy, brushed it onto the stripped area going right to the masking tape. Laid pieces of CF longitudinally along the chainstays. Then wrapped the CF strips turn by turn, wetting it out as I went and pulling it tight.after wetout. I took turns around the support as well as the chainstays. Taped the still dry end again firmly to the painted chainstay. But things started going badly. The CF was too stiff and the epoxy resin wasn't breaking down the binder in the fabric so it was springing away from the metal. This as the epoxy was starting to set up.
Ran in side, grabbed my thinking cap and thought fast! An innertube wrap. A crude vacuum bag. Cut tubes into two strips each. taped them just like I did the CF and wrapped it tight! Lots of resin squeezed out. I knew it had set up enough that doing anything would be a disaster so I spread newspaper and left.
Next day, I returned fearing the worst. Unwrapped the innertube which came off nicely to see a finished job that looked vacuum bagged! Took a sharp knife to trim the CF right at the tape edge and pulled the tape. Nice and clean. Sanded it just enough to remove hairs and owies. (Later I had to grind the CF down to clear the chainring but that was well past the crack so the cut fiber didn't matter. The point was to not cut or jeopardize any of the CF strands to keep full strength.) Finally I painted the repair black. (On a red bike.)
End result? It turned the typical loosey-goosey Peugeot BB into the stiffest Peugeot ever made. Never worried about that crack (or anywhere else around the BB) again. Rode it 8000 miles. (I did not take it into the hills, but not because of that repair. I had no idea what else on that frame was compromised when that SUV hit it and had no interest in finding out going downhill.) The frame is now retired. I've suffered two hard crashes on it (not its fault and it came through far better than I) plus I wanted a bike that much fun I could take into the hills so my avatar was patterned after it to take its place.
Sorry, no pics.
Ben