Creating an Automator service to add email messages to Reminders.app
I don't have the keyboard shortcut, but I just finished an Actionscript that adds the email Subject as the Reminder Title, the email Body as the Reminder Content and then adds a link to the actual email at the bottom of the Reminder. Hope this helps!
on run {input, parameters}
tell application &quot;Calendar&quot; to activate
tell application &quot;Calendar&quot;
    set miniaturized of window 1 to true
    tell application &quot;Mail&quot;
        set theSelection to selection
        set theMessage to item 1 of theSelection
        set theurl to &quot;message://%3c&quot; &amp; theMessage's message id &amp; &quot;%3e&quot;
        set thedes to theMessage's content &amp; &quot;Show in Mail &quot; &amp; &quot;message://%3c&quot; &amp; theMessage's message id &amp; &quot;%3e&quot;
        set input to theMessage's subject
    end tell
end tell
tell application &quot;Calendar&quot;
    tell application &quot;Reminders&quot;
        make new reminder at end with properties {name:input, body:thedes}
        tell application &quot;Reminders&quot; to activate
    end tell
end tell
return input

end run