by nova
25A to current Star Wars arms...as far as I've seen all you have to do is warm them up and pop the lower arms from the upper arms...then mix and match as you see fit. Either some hot water or a hairdrier are perfect for applying the needed heat.
other than just switching around feet between Joe and SW...you're going to have to do some surgery...
To put Star wars legs on a Joe torso...You'll want to cut both legs at the thighs...Cut extra...its easier to take away material than it is to add it. I would use a dremel to hollow out the SW thigh so the Joe thigh can fit into it and give you more surface for a glue of your choice to hold.
When you cut the Joe thigh...remember you need the screw to hold the leg together...I would cut just below where the screw is.
I can't immagine any situation where you'd want to put Joe legs on a SW crotch...if you're that set on eliminating articulation....you can just glue the joe figure's joints and be done with it.