Longpress on non-repeating keys of keyboard-remote

I’ve just recently set up OSMC on a Raspberry Pi 3. To control it I’m using a remote I got with a kickstarter mediacenter that turned out to be less than fantastic. The remote is kinda nice though, although it only has 12 buttons total, making longpress a necessity. However, 4 buttons are for non-repeating keys.

As I understand it, key-repeating is necessary for longpress to work. The keys all make sense to be non-repeating (power, mute, play/pause, home), but would work well with longpress. As I see it, there are two possibilities:

  1. Enable repeating for the keys.
  2. Remap the keys to a repeating key before they hit whatever layer makes them repeat.

I’m not very proficient in linux, though, so I have no idea how to do this or if it’s even possible. Can anyone help? Any other suggestions?