Yep, it'* a pain to replace the water pump on the supercharged '92/'93.
Like you saw, the alternator bracked is in the way of that last bolt on the water pump, so you have to put a socket thru the holes in the power steering pump pulley and remove the 2 bolts there, then drop the power steering pump a few inches out of the way, then you'll see the remaining hidden bolt(*) for the alternator bracket so you can remove them and move the bracket an inch or two out of the way so you can remove the last water pump bolt.
When I did it on my '93 last year, I was amazed at how GM designed it...it took me about 5 hours to replace the water pump, and that'* about what the dealer said they charge for their time. I suspect that it'* MUCH easer on the non-supercharged engines for those model years.
'99 Bonneville SLE, white, 112,000 miles
'02 Park Avenue Ultra, white diamond pearl, 88,000 miles