Something

on *:TEXT:`setgreet*:#: {
  set %greet $+ $nick $2-
  msg $chan 15 $+ $nick $+ , Your greet for $chan has been set to:15 $2- $+ .
}

on *:TEXT:`unset*:#: {
  unset %greet $+ $nick $2-
  msg $chan 15 $+ $nick $+ , Your greet for $chan has been unset $2- $+ .
}

on *:JOIN:#: {
  if (%greet [ $+ [ $nick ] ] != $null) { msg $chan $nick [ $+ $nick $+ ]: %greet [ $+ [ $nick ] ] }
  if (%greet [ $+ [ $nick ] ] == $null) { notice $nick To set a greet for $chan type: [ `setgreet (greet message here) ]
  } 
}