On QUIT isn't a channel based event. When someone quits, they 'part' all channels. So you have to use:
Code:
on ^*:quit: {
var %x = $comchan($nick,0), %y = 0
while (%y < %x) {
inc %y
echo $comchan($nick,%y) * $nick has quit.
}
haltdef
}

Untested, but thats the basic idea.

Those who can, cannot. Those who cannot, can.