I've got the rusty's Shackle BB, and I'm pleased with it, I now have the urge to go taller... but since I got the shackle lift I can make a 3" kit 4 3/4" by keeping the BB on there. I've heard that the AAL cause a slightly rougher ride, but I don't know. I will say that with the shackles, the rear of my XJ (99) is sagging a bit and I'm going to put a 1/2" block in to bring it back up. As for the specific directions on how to do, I went to rusty's website and the how to section, or tech section or something like that.
Any questions let me know.