I just came here to say the same as Obilolo - thanks to this thread, this was one of the most satisfying troubleshooting experiences I've ever had. Not only did I make an old remote thrown in garbage as useful as a $60+ multimedia remote -- but as a Linux beginner I just had cause to research for a few hours and learn a heap about computers and operating systems along the way.
HiassofT - your meticulous and detailed instructions and persistence to help someone for no personal material gain is outstanding.
For Australian/NZ users looking for a cheap remote with lovely click-y buttons: the plethora of old Foxtel boxes being thrown away means you get a Foxtel IQ3/4/5 remote (the one with microphone*) which uses bluetooth and may be paired with Pi for ~$15 on ebay.
The centre 'select' button is recognised as KEY_SELECT. I added the following for Kodi to recognise:
evdev:input:b0005v06E7p8144*
KEYBOARD_KEY_c0041=enter
[*I should say I haven't yet experimented if the microphone will be useful in Kodi but that's for another thread I'm sure.]