I expanded on this a little

Someone says "!welcome [message]" and it sets that to be their join message. When they enter it will be that message

The $read(sreglist.txt,nw,$nick) is my list of nicknames that i want to have a join message (so it's not spammy)you can easily replace it with if ($nick isop $chan) {
on *:join:#: { if ($readini(Welcome.ini,Messages,$nick)) msg # $v1 }
on *:TEXT:!welcome *:#: {
if ($read(sreglist.txt,nw,$nick)) {
if ($readini(Welcome.ini,Messages,$nick)) {
remini Welcome.ini Messages $nick
msg # changed $nick $+ 's welcome message to " $+ $2- $+ "
.timerWriteWelcomeMessage 1 1 writeini Welcome.ini Messages $nick $2-
}
else {
msg # set $nick $+ 's welcome message to " $+ $2- $+ "
writeini Welcome.ini Messages $nick $2-
}
}
}