hey guys, I stopped scripting for mIRC ages ago, but this is what I've found in my remotes:

raw 474:*: {
var %i 1
while (%i <= $0) {
if $left($gettok($1-,%i,32),1) == $chr(35) { set %rw.chn $gettok($1-,%i,32),1 }
inc %i
}
echo -a Cannot join. You are banned in : $+ %rw.chn
if (!$hget(unable,%rw.chn)) {
.msg chanserv unban %rw.chn $me
.timer 1 5 join %rw.chn
hadd -m unable %rw.chn banned
}
haltdef
}

try it out and let me know if it works. I see it has added some loop prevention with hash tables so I guess it should do the trick.