You should make it to have the ability to input the password, rather than have it hard coded in the snippet by itself:

alias id {
  noop $$input(Put Your Password Here:,p,Nickname Identify)
  ns identify $!
}

this way it's easier and convenient for people who are interested in using your snippet.

If this is for personal use only, you can put the /ns identify cmd directly inside mIRC's perform box without using an alias. To read more, enter: /help /perform