You need to find the ASCII value ofthe FN F6 Value, I found someone reporting it as 258 or {(ASC 258)} but this shows on the ASCII Table as F8, Your keyboard makes FN+F6 act as a single keystroke (Usually equal to something between F13-F24) although keyboards dont tend to have these keys they still have values, the FN key basically extends the F Keys to a second row, the value will depend on both the hardware (keyboard) and the driver.

Trying not to ramble on you will need to capture your ascii value by pressing FN+F6 with an app that will translate it.

Edit: Keycode values, not ASCII values, the Fx Keys dont have ASCII values

Edit 2: This site may give the result (scroll to test box at the bottom of the page)
http://www.quirksmode.org/js/keys.html
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