I haven't had my hands on one to convert to figure out the details. I saw a thread on another forum where people had done it. I assume that you would drill, tap, and plug the current firing pin hole in the breech block and then drill a new passage. Or possibly an offset firing pin.
There are many lightweight .32 centerfire cartridges. Most are loaded to blackpowder specs. One of them, I think .32 long, was intended to duplicate the .32 rimfire ballistics. If you wanted to be very safe, there is a .32 short that is very low powered.