Next time you connect to a server it will ask you the questions needed to add this to your ajoin.

on *:START:{
  server irc.nixtrixirc.net
  play aserver2.txt
}

on *:CONNECT:{
  if ($read(aserver.txt, w, * $+ $network $+ *) == $network) {
    if (% $+ $network $+ .chans) {
      if (% $+ $network $+ .pass) {
        msg nickserv identify % $+ $network $+ .pass
        join % $+ $network $+ .chans
      }
      else {
        set % $+ $network $+ .pass $?="Enter NickServ Password:"
      }
    }
    else {
      set % $+ $network $+ .chans $?="Enter Auto-Join Channels:"
    }
  }
  else {
    if ($?!="Do you wish to add this server to auto join?" == $true) {
      set % $+ $network $+ .chans $?="Enter Auto-Join Channels:"
      timer 1 0 set % $+ $network $+ .pass $?="Enter NickServ Password:"
      write aserver.txt $network
      write aserver2.txt /server -m $serverip
    }
    else {
      halt
    }
  }
}

alias serveradd {
  if (% $+ $network $+ .chans) {
    echo This network is already on your ajoin!
    halt
  }
  else {
    write aserver.txt $1
    set % $+ $network $+ .chans $?="Enter Auto-Join Channels:"
    set % $+ $network $+ .pass $?="Enter NickServ Password:"
    write aserver.txt $network
    write aserver2.txt /server -m $serverip
  }
}