Jig? you mean a piece of pipe to press the bearing and retainer back on? sch80 gas pipe is the right inner diameter and it is thick enough too.
The I live in an apartment or I want to know how to do this on the trail method:
To remove collar and bearing: remove axle assembly from truck. Cover the brake line union with a rag because it is going to squirt all over. Remove cir-clip. With brake drum still on the axle for the added mass, put a piece of wood on the floor, point the end of the axle at it and slam the assembly down like you mean it. do it a few more times and tada. Bearing and collar removed. To reassemble, you can also tap the bearing and collar back onto the shaft with a nice brass drift. (not a steel chisel)