I'm trying to remap my keyboard such that the Caps Lock acts as an additional Fn key, because the current one is in an awkward place (over by the Home and End). I was planning on using xmodmap, which requires keycodes to work. I have my Caps Lock keycode, which is 66, but to finish I need the keycode for the Fn. Using xev and pressing the Fn, I don't see anything. Any recommendations?
The Fn key usually doesn't send a key code; it's handled by the BIOS, not by the OS. You can sometimes get at it as an ACPI event. (This is very much dependent on the exact computer model.)