I figured it out with help from a Jeep forum, and will try to describe it precisely for future generations below:
(Incidentally, for those who don't already know, the Jeep forums are an excellent resource for Eagle owners, especially when you can't get enough info from the Den...)
The PS pump is held by an aluminum housing, which is in turn bolted to a steel bracket. You are going to move the aluminum housing relative to the steel bracket (not the PS pump relative to the aluminum housing, as I originally thought). There are only two things you have to loosen:
(1) The pivot bolt, so the housing can rotate. This is a 15mm nut on the back of the alum. housing at its top, and is partially hidden by a small tab of the steel bracket that bends towards the back of the car. This nut can be a little hard to see and get to; on my car the EGR hose ran right behind it, and I had to collapse the hose a little to make room for my socket and wrench.
(2) The 9/16 inch clamping bolt, which locks the housing in position. If you're looking at the housing/bracket from the front, the clamping bolt is about level with the pulley's axle, and about 2 inches to the left of the near edge of the pulley (or about 5 inches from the pulley axle, if you prefer). Loosen this bolt, and leave your wrench on it so you can tighten it with one hand while you rotate the housing with the other.
Rotate the housing by using a 1/2 inch drive socket wrench in the square hole on the back side of the housing, then lock it down with the 9/16 inch clamping bolt. Finish by re-tightening the 15mm pivot bolt nut.
This description is probably overkill for most of the ace mechanics on this board, but some newbies may find it useful. Just seemed like it ought to be spelled out out exactly somewhere...
JB