It should be pretty similar to replacing the suspension arms I'd have though.
To replace the upper suspension arm you need to drop the suspension leg to get the top plate off, so I'd start with that and see how you get on.
to do that its a case of jack up, remove the bolt that goes through the lower arm and suspension leg, unbolt at the top (upper suspension arm ball joint) and unbolt on the suspension turret in the engine bay and it should drop down.
You might with a set of spring compressors be able to get the shock out at that with some wiggling.
All a bit theoretical as I've never had to completely remove the suspension leg myself but worth a shot.
Don't bother trying to unbolt the shock from the suspension leg support, it'll be seized solid and never move, so you'd be wasting your time.
1999 156 1.8TS Sport Pack 3
2001 166 3.0 V6 24V Super
2003 156 GTA 3.2 V6 24V
2005 156 1.9 JTDM-Jet Sport
2008 159 1.9 JTDM Lusso
1997 GTV 2.0TS Lusso
2001 147 1.6TS Lusso