I have a good supply of roxul scraps and i want to shred them up to the consistency of the roxul attic insulation they sell here in canada. I tossed some into the cellulose blower and it does grind it up some what but it clogs easy. anyone have any methods to grind it up or have done this before?

Unfortunately the batts are manufactured with binders, that will always make mere shredding with blower hopper tines incomplete. You'd have to come up with something that would slice & dice them to a reasonable sized granule, sort of like the AttiCat fiberglass stuff.

cut into strips and run through the hopper of a wood chipper/leaf shredder would be my best guess.