Code:
on *:join:#: {
  if ($readini(Welcome.ini,Messages,$nick)) msg # $v1
  else { 
    if (%floodwelcome) || ($($+(%,floodwelcome.,$nick),2)) { return }
    set -u10 %floodwelcome On
    set -u99999999999 %floodwelcome. $+ $nick On
    msg # $readini(Welcome.ini,Messages,Unknown)
  }
}
So just create an ini file called Welcome.ini that looks like this:

[Messages]
User1=Hello $nick how are you
User2=...
User3=...
Unknown=...

You make an alias or something to add messages as well, just use
Code:
writeini welcome.ini messages $1 $2-