MQ2Map has a few nifty features that aren't well documented. The first is you can see what click commands are active as follows:
/mapclick list <-- lists the commands associated with the Right mouse button + key combos
/mapclick left list <-- lists the commands associated with the Left mouse button + key combos
For example, on my setup:
/mapclick list:
ctrl: /maphide id %i
lalt: /highlight id %i
/mapclick left list:
shift: /bcga //nav locyxz %y %x %z
shift+ctrl: /nav locxy %x %y
The 3 non-bold entries are default, I believe (and shows you ctrl+shift+left click was what you were looking for). I added the bolded line by editing the MQ2Map.ini file and adding the following:
[Left Click]
KeyCombo1=/bcga //nav locyxz %y %x %z
This lets me move my whole group to where I click on the map - very useful when they are not chasing (e.g., paused).
Note that you would think a section [Right Click] would work for the right mouse button, but I could not make it do anything.
I did some testing, and here are the KeyComboX values I discovered:
KeyCombo1=SHIFT
KeyCombo2=CTRL
KeyCombo3=CTRL+SHIFT
KeyCombo4=L-ALT
KeyCombo5=SHIFT+L-ALT
KeyCombo6=CTRL+L-ALT
KeyCombo7=CTRL+SHIFT+L-ALT
KeyCombo8=R-ALT
KeyCombo9=SHIFT+R-ALT
KeyCombo10=SHIFT+R-ALT
KeyCombo11=CTRL+SHIFT+R-ALT
I don't know exactly what % parameters are passed to the command, but I can surmise at least the following:
%i - ID of the mob clicked on
%x, %y, %z - coordinates of the click
Having done this exercise to answer your question, I now know why my shift-click and shift-ctrl-click actions do different things in zones with multiple levels - one includes Z and the other does not. I think I will try setting up combos that use X,Y and X,Y,Z for both myself and group so I can use the appropriate one depending on the zone. For those interested, here is what I switched to (now to get used to it):
[Left Click]
KeyCombo1=/nav locyxz %y %x %z <-- SHIFT, just me
KeyCombo3=/bcga //nav locyxz %y %x %z <-- CTRL-SHIFT, whole group
KeyCombo4=/nav locyx %y %x <-- L-ALT, just me
KeyCombo6=/bcga //nav locyx %y %x <-- CTRL+L-ALT, whole group
Anyway, sorry for the long post. Hope it helps someone.