Thank you for your replies.
After some further investigation it appears the files for the backlighting of the VC are present in the texture folder: vc_01_l.bmp and vc_02_l.bmp. However, their presence does not seem to do anything. I loaded the VC model into modelconverterx and those textures are not called anywhere, as far as I can see, but in an original posky 777 for fs9 they are not called either.
I have managed to make my own textures to make it a dark cockpit with only the buttons / text lighting up, but the gauges stay dark. I did attempt to use a modified VC light fx and placed it near the screen, which worked okay, but not great. However, there is a limit on the number of lights in a aircraft.cfg, so this method is out.
I don't believe Rikooo has any 777 which is compatible with v4, but I would love the link if there is one.
Here on the Rikooo forum, in v3, you can see the backlights working: https://www.rikoooo.com/forum/265/46297