in the materials.lua file, there is a portion, line 27 for LMDI
Below that is RMDI, and below that is HI (which is the AMPCD)
MDG_materials[MDG_SELF_IDS.LMDI] = {255, 255, 255, 255} -- MDI original
MDG_materials[MDG_SELF_IDS.RMDI] = MDG_materials[MDG_SELF_IDS.LMDI]
MDG_materials[MDG_SELF_IDS.HI] = MDG_materials[MDG_SELF_IDS.LMDI]
By Default the RMDI, and HI (AMPCD) both reference the LMDI for color. All you have to do is replace the section after the = sign (MDG_materials[MDG_SELF_IDS.LMDI] section) with your RGB color codes, and a 255...
Example: MDG_materials[MDG_SELF_IDS.HI] ={255, 0, 29, 255}
Will make the AMPCD text red.
You can also do the same for RMDI if you want it a separate color from the LMDI. This will allow a different color for each MDI if desired. I personally made my L and R MDIs white, and the AMPCD red. this seemed to be the best readability in VR for me... (I am still tweaking things though)