I know this is a very old thread but just to close the loop on this subject, it certainly IS possible to change the CV boot by removing axle "A" from CV joint "I" without removing the CV from the knuckle.
It does take a knack and a helper (or a third arm) but with the rear control arm disconnected at the sub-frame end and the suitable application of a suitable force in a suitable location, the axle will pop out of the CV inner pretty easily. Slip off the old boot, slip on a new one, re-grease the joint, close up the boot etc...
