The 46b
doesn't have the standard .22 cut grooves in the top of the receiver. But it does have two screws on the receiver that can be used to mount an adapter like this..
With that mount, you can use regular Weaver style rings. Here's the link the one Numrich (gun parts) sells..
Side Scope Mount, Weaver Style
It's not cheap, but it's simple..
You could also have a gun smith cut grooves for standard size .22 scope mounts, but that would be more expensive than the Gun Parts Mount, and a $15 set of Weaver style rings..
Either way, it can be done.. Good luck, and when you're done be sure to show us some photos!! Also, the link given earlier to Havlin Sales is one to keep!! Havlin is the place to go for all things when it comes to old Mossberg .22!! Great people and VERY helpful!! They also stand behind what they sell!!