Make sure you have the latest VCE.
Events:
Onactivate--->self--->fireRelay
OnRelay--->Self--->fireRelay
OnRelay--->Self--->VCE_ifValue [<var:player:firing>][===][1][you can leave this empty for now]
OnVariableTrue--->Player--->Spawnprojectile--->[speed of projectile][alarm]
Activate the evented brick in first person, and you'll fire bullets for as long as you hold your left mouse button.