Following his
original article on Instructable, I started looking around this forum for posts containing the word "keypad" (using the advanced search, also tried "keyboard" but it seemed less apt). Examining his code, I found the
echo "send 109" > /proc/keypad, which worked a treat. Searching further I found the
"USB Device to turn the page" thread which lists a variety of outputs of various numbers. Alcorns
Voice control thread has some good pointers, especially a reference to a
"kindle terminal" that contains
keydefs.ini. But I don't really know how to reverse engineer an .exe. A thread on connecting
a external keyboard, which was fairly similar to one one
simulating button presses had some interesting links, as did
"merged terminal/launchpad/web server".
Ultimately I could not find a reference onhow to send input into the virtual keypad on the K4NT via SSH - as it was not as simple as sending them as button presses (as I was hoping), and thus I was hoping maybe someone knew this or knew about a post that covered it. I might just not have used the right terminology for it, but "keypad" and "keyboard" seemed the best to describe it.
Belated note: Thanks for that link twobob, it seems like exactly what I was looking for whilst writing this summary.