I don't know of anyone who sells a jig for that purpose or if any exist outside the Ruger factory and maybe a few custom grip makers. At one time, you could buy semi-finished grips for a variety of guns, but I haven't seen any for a while and none for that gun turn up on net searches I did.
Dixie Gun Works sells unfinished one piece grips for the Colt 1851 frame, but you can't use a one-piece; you would have to cut them and I don't know if they would fit though they are plenty big. You might try though, if you want walnut, they are only $5 or so.
In other words, sounds like you need some material (whatever you want to use), some basic tools, and a bit of luck.
Jim