What sorts of locks/permissions does this file have? Maybe you could make a tool that lets you make changes, schedules a modification of this file on next rest

What sorts of locks/permissions does this file have? Maybe you could make a tool that lets you make changes, schedules a modification of this file on next restart, and after the restart it propagates the changes in the registry too. Yes, "please reboot to apply your new mouse position^W^W^Wfile association changes", yay, but that'd work. Although I'd definitely hate it.