There should be enough movement on the PS pump and the compressor to remove the belts without removing any bolts - assuming you have the proper length belts installed. I'm pretty sure I've read threads where people talk about a longer- or shorter- belt to either stop squeal or adjust.

The PS pump and compressor each have three mounting bolts and one adjusting bolt - pretty much as you described. I've got some pics in my thread here: http://www.peachparts.com/shopforum/diesel-discussion/281663-installing-compressorworks-r4-into-w123.html

They are in the same orientation: upper inboard = pivot, two other mounting bolts swing/rotate, fourth small bolt adjusts tension or position. On the W123 R4 compressor and bracket that's a eye-bolt.

Are you sure it's the A/C lines causing the compressor to not move? On my car the oil cooler line was in the way. I had to loosen the oil cooler hose mounting bracket.

I think Tango's intent would be for you to set the correct tension on the belts BEFORE trying to remove them to isolate the noise. You can also just turn the compressor off, and the pulley should spin freely without any compressor load. Turn it on, then listen...