Created a spritesheet with five 16x24 sprites (80x24 total) to replace the XP progress icons in the HUD. Call it "XPIcons.png". The leftmost (first) sprite being the empty progress and the rightmost (last) sprite being full progress.

An example has been given called "XPICons_example.png". Renamed it to "XPIcons.png" to see it in-game.