Complete soil flush and re-pot-how to?

Ok so i wont to totally remove the roots and wash them out really good and maybe use superthrive also. I want all new dirt. How can i do this and get all the dirt of from in between the big root mass without causing to much stress. I want to totally re-pot

Get a 5 gallon bucket and keep soaking the roots until you get all the dirt off. If you have a sprayer on your kitchen sink you can keep spraying the roots into the bucket until all the dirt comes off. You'll just have to work at it and not get in a hurry. I think sprayin over and over, emptying the bucket over and over is the easiest.