I’d like to mount a button to my spindle that releases the drawbar for manual tool changes.
Look at my wiring diagram here:
You want to take the + power from the 24v power supply in your box, run it to the button (which is momentary closed – ie: it closes when you hold the button down), and then run it to that 2+ side of your relay (just add it in under the bolt with the other), which should go to the pneumatic solenoid. The other side, -1, should go to your 24v supply.
You could also run the 24v to power the relay itself, like what you are talking about. But you’d have to isolate the flow with diodes, so it is more difficult. You don’t want to back feed 24v to your 5v signal on the control board, it might fry it!
When I set mine up, I did it this way (with diodes), but the way I talk about in the diagram is gobs easier.
Thanks for that Corbin.
Seems I’d overlooked your reference to the switch when scanning through the docs earlier.
In the case of my machine’s relay switch wiring the button’s neg(-) wire needs to run to the relay’s -1 side. The relay’s -2 side is headed back to the 24v power supply’s neg(-) side.
Regardless, now I see that we’re just using a relay switch to bypass a relay switch.
Smarter every day 
Giddyup!
