Without trying it, I wouldn't expect that it would be easy to get a good approach with a hand drill unless your output shafts are out. I also believe they are hardened and if so, that would make it more difficult still. Worried about spares? Get several sets of pins from r.d. Call me chicken, but I think using the prescribed parts is a better way to go. After all, are you planning on replacing your roll pins often enough to require more "standard" sizes?