I got it to work, more or less.
/macro C "powexeclocation me Caltrops"
It works on my Defender who has Traps/ and my Corruptor who has /Traps. It is not, however, working for my Blaster who is /Devices.
For the Blaster, it puts a red ring around the Caltrops power button, as if it is a power queued up and waiting to go, but it doesn't activate.