How hard is it to put in a B&M shift kit on the 4L60E?

I wanted to know would you have to take the tranny out and if so what other kits can you do without taking the tranny out.

I'm not familiar with the B&M kit but the Transgo requires removal of the pan/valve body and is pretty involved. I bought the kit months ago but haven't installed it ($250 estimate). My car is doing fine with the Predator, and HPP3 before that.