okay so the OP should be pleased I am bored - I am sat looking at the eLearn description for this.
according to eLearn.
1. remove the door corner cover using the special tool (read your favour screwdriver).
2. Remove the door grab handle / window switches. do this by removing the rubber mat in the bottom of the grab handle and undo the 2 nuts, then lift up to release / disconnect electrical connections.
3. Remove the courtesy light on the bottom of the door card, one edge of this should just unclip and hooks in the other edge, so pop one end out then unhook.
4. Remove door card. there is 3 screws in the door jam, 4 along the bottom, 3 along the outter edge. also remove the door handle surround and remove the trim cover. Next "move the panel slightly releasing the inner retainers using special tool" - theres that screw driver again! Then it says remove the retainers for the door handle, disconnect the wiring and remove door card. not sure about the door handle bit and don't rely on the screw count.
The rest seems pretty straight forward.
There are 3 bolts that hold the mirror on, one of which is underneath the door seal so you have to pop a clip and remove that. There is the wiring that runs between and the drivers door junction unit (door ECU).
you will need to disconnect the battery for this BTW.
the special tool it refers to is literally given the description "knife".
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