because the key can be removed probably, anyway:
Say #chatzone was the channel, well add this to your remote section (ALT+R)
alias chatzone {
join #chatzone key
}
Then you would type /chatzone and it would work

You can modify it to fit your needs, chatzone is the command you would type, and there must be a space between alias the word/command and that {. Then below is the command that will happen once '/chatzone' is typed. You don't have to prefix it with a '/' in scripting.