hmm looked up the Merc type compressor - goes up the middle not outside the
spring?
ends up costing most of £200 pounds to get here (UK)
I've never done a car spring, but done a couple of bike units, but I can't
see why an ordinary car spring compressor wouldn't work, unless the springs
are incredibly long?
Looks like it would need plenty of offset for an ordinary type compressor to
clear the 'swinging arm' thing the bottom is mounted on, though
must get to a tool shop and eyeball some compressors...

cheers!

These tools - spring compressors - aren't too expensive - EBAY here's one for $55, that should suit your needs, and another, pro one - EBAY for &100 plus &46 s&h.. Well, there even are ones for a few bucks, but with these you have to know, what you're doing - or decompressed spring, after sliding off will make a lot of mess....
Whole thing is rather simple, but requires few things - spring compressor, lever offering stable position of a car (not one from original equipment - will make problems when unscrewing hard screws and shaking all car when lying under ), good manual (like one form Wis/Asra) and have enough accessories (keys) to disassemble and remove fornt macpherson. And a lot of free time for DYI :)