Ah well.... I recall this job. Actually done this twice on my '88 S4.

I would recommend doing both boots per axle at the same time. It is just a little more work if you do both. I left the axle nut on which saved a lot of trouble. (read on my website or the a.m. Nichols tip) I had my fight with the axle nut once and am not someone to give up easily. Fixing the boots without removing the axle is no big deal unless you have to wash out dirt from the outer CV..
It was quite easy but a messy job. Agreed. Slippery is the right word. A few hours per axle is required and some room under the car preferably (lift or pit). I just lowered the exhaust a bit.

One more tip: make sure the position of the end that closes the boot to the axle is right before you put the clamb on tightly. If there's too much tension on the rubber boot you will have a tear again pretty soon.

regards,

 

That may explain why Brian's only lasted a short while.