You can also add these aliases *assuming you dropped winhlp32.exe into your mircdir

Code:
alias F1 run winhlp32.exe mirc.hlp


and to open mirc.hlp at a specified keyword, single keywords only though.
ex. "/help /alias" works fine but "/help address book" doesn't

Code:
alias help run winhlp32.exe -k $iif($1,-k $1) mirc.hlp