I'm trying to create a custom panel to set global variables. The problem is I'm unsure of how get at whatever value i type into an input field in the custom panel and pass that to my script
I see the cuquery command as perhaps the only option, but i was rather hoping i could just have a button in the custom panel that would drive a script with the custom panel values being fed to the script as arguments.
Something like
Pfoo/bar/doStuff.cmd in.val out.val
wishful thinking no doubt.
I tried messing around with cuquery, but i guess i'm just screwing up the syntax.

I thought that we had such documentation already but seems to be gone now.

Try these local variables in your scripts:
CUG - path to current gadget
CUP - path to current panel
V - value of current gadget