Code:
on *:Start: {
  server server.one address -j #channel1
  server -m server.two.address -j #channel2
  server -m server.three.address -j #channel3
}

on *:Connect: {
  if ($server == server.one.address) { nick Whatever }
  if ($server == server.two.address) { nick Whatever }
  if ($server == server.one.address) { nick Whatever }
}