You can use SendKey to mimic keyboard inputs ( http://msdn.microsoft.com/en-us/library/system.windows.forms.sendkeys.send.aspx )
Code:
alias sendkey .comopen a WScript.Shell | .comclose a $com(a,SendKeys,3,bstr,$1-)
/sendkey +{F1} would mimic shift+f1 on the keyboard, note that mirc might not be the active application when your event trigger.

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