Jon, I never tried to move a large one like that, but I know they are easy to root. Snip off a few sprouts of last spring's growth about 9-12 inches long and just stick'em in some dirt or potting soil. Most of them will sprout out in the spring and be ready for transplanting the following spring. You might want to try starting some new ones this way before attempting to move the big one, just in case the move doesn't go well.

You may be able to move the plant in sections, if it has multiple sprouts coming out of the soil. Just do a little exploratory digging to see what the root system is like. From what you said, it sounds like it is more than one plant.