Someone

on *:TEXT:!setgreet*:#: { 
  set %greet [ $+ [ $nick ] ] $2- 
  notice $nick Your greet message has been set to: $2- 
} 

on *:TEXT:!delgreet*:#: { 
  unset %greet [ $+ [ $nick ] ] 
  notice $nick Your greet has been deleted 
}