Thank you. You can do it like this:
Code:
on !*:join:#:{
  var %u = 1
  while ($ulist(*,admin,%u)) {
    if ($nick == $v1) {
      msg $chan Admin $v1 has joined $chan $+ !
    }
    inc %u
  }
}
This will send a message to any user added with "admin" access in the user list.

If you're gonna match with other accesses you've added, the code will need to be modified. Currently it will match the admin only.