Hitting the "Swap" key on the keyboard will bring online all cued items in the Sequencer. The Swap key is the forward slash key on the numpad.
As for setting this up as a trigger, can you check on your keyboard map if you have the swap channels keyboard shortcut? I can't remember what version that was added to.
XPression > Edit > Keyboard/GPI Map > Available Global Functions > Channel Functions > Swap Channel
#XPression