Use the group option suggested earlier
example:
Code:
on *:text:!notice*:#justin.tv:{
  if !$2 {
    .msg $nick Join notice for $chan is $group(#join)
  }
  elseif $2 == on && $group(#join) == off {
    .enable #join
  }
  elseif $2 == off && $group(#join) == on {
    .disable #join
  }
}
#join on
on !*:join:#justin.tv:{
  .describe $chan welcomes $nick to $chan
}
#join end