One little known feature in mIRC is that by typing /<anything> mIRC will run any help file in the mIRC directory that has the filename <anything>, if that command doesn't already have another purpose.
Try this test alias to see what I'm talking about:
alias test {
versions.hlp
return
:error
reseterror
write versions.hlp
echo -a Error caught, versions.hlp written, now attempting to call /versions.hlp again.
versions.hlp
}
You can also omit the .hlp|.chm file extension and just use /versions instead.
This is also why /mirc and /ircintro open their respective help files.
Edit: this is more of a reply to everyone stating that /mirc.hlp isn't a command rather than to you Wims.