you can use VCE by putting in relays, and on the relay loop,
[0]onActivate->self->fireRelay
[1]onRelay->self->fireRelay
[2]onRelay->self->ifValue->[<var:pl:firing>]==[1] [3 3]
[3]onVariableTrue->Player->spawnProjectile[whatever you want]
you can also replace <var:pl:firing> with any number of things from the manual and it'll work still