Tool Change setup

No experience with that type, but i would sure have a look at doing that with some gcode subs that would be called instead or when a tool change is called for, something in the lines of:
M6T3
subT3
Raise Z
Goto XY coordinates of tool 3
activate output for valve
lower Z
deactivate output for valve
raise Z
move on to do the work
That would also need some logic for checking what tool is inserted etc etc.

Cpk_Rbt wrote:

I've started looking at the sim.axis.remap.rack-toolchange example, but it seems overly complicated for what I need.

It probably isn't. You do need to take account of what happens if a toolchange goes wrong, and the example probably does that.

You can take it in stages. First write a G-code subroutine to run the tool-change, then do the re-map to get it to be called automatically with an M6. (or with a Tnn if you want to be unconvetional).

The example rack_change.ngc is likely to be very close to what you need.

Note that it calls this routine to calculate the positions and that expects a section in the INI that defines the absolute position of the rack and the spacing between the pockets and to make that work you need to turn-on INI access from G-code:
If you prefer you could, for your machine, hard-code the numbers in the G-code subs.