Microsoft Remote Keyboard for Windows XP Media Center Edition v1.0 (Model 1044) in LibreELEC/Kodi
After many hours of frustration trying to get this keyboard to work with LibreELEC 9.2.0 (the latest version as of this writing), I eventually came across a post suggesting to downgrade to 9.0.2 because of a bug in 9.2.0. Although the keyboard still didn't work after I installed 9.0.2, I was able to get it working by adding the "mce_kbd" protocol, which never worked when I tried it in 9.2.0 (only the arrow keys on the keyboard, and no mouse functionality). I would therefore like to make others aware of this, and to also offer a little tutorial on how to get it working with 9.0.2.
Assuming you have either downgraded to 9.0.2 (some add-ons didn't work for me after doing so), or done a complete reinstall (which I eventually did), the procedure is as follows:
Login via ssh by typing "ssh root@your_libreelec_ip_address" (without quotes), and enter "libreelec" when prompted for the password (unless you have set a custom password).
The ip address part can be found in network settings in Kodi. It will be something like 192.168.1.2
Once you are logged in, type "ir-keytable -p rc-6 -p mce_kbd" to add both the rc-6 and mce_kbd protocols. If they are supported by your infrared receiver, they should be displayed under "Supported protocols", and if they have been successfully enabled, be listed in the "Enabled protocols" section. Type "ir-keytable" to check.
If everything went ok, then type "cp /usr/lib/udev/rc_keymaps/rc6_mce .config/rc_keymaps/ms1044".
Now type "nano .config/rc_keymaps/ms1044" to edit the file.
Change the top line to "# table rc6_mce, type: RC6,mce_kbd" (without quotes) to also enable the mce_kbd protocol.
Press Ctrl + O to save the changes, and Ctrl + X to exit the editor.
Now type "nano .config/rc_maps.cfg" and add this line to the empty file "* * ms1044" (as usual, without quotes).
Save file and exit the editor.
Reboot Kodi and you should now have a working keyboard and mouse.
Also, don't forget to disable automatic updates for LibreELEC so that it doesn't update to 9.2.0. Set the updates to "manual" in the LibreELEC section of Kodi options.