Prepare for my blurry low resolution pictures of a modified Metroliner:
Some information, why I didn't just connect the extension cable to the light brick at the front: the old 9V electric cable broke, so I used my PF lights and some ideas laying around to make it go again (and light up of course).
As seen here, the dummy engineer can still sit comfortable at his console and do his work. Also the battery pak is easily removable.
Once again, some Emerald Night leftovers were used to support stuff, like the IR receiver this time.
Old Light Prism still in use and lighted with your handy PF lights, not that hard to pull of, old light brick used for stability.
The IR receivers cable is routed on the left side of the battery, to keep the LED free.
And use a simple method to switch it on and off without removing or opening anything:
Final product and light testing. There was enough cable to light the bar at the back.
Alternatively the IR receiver could be installed in the back and nothing much would happen at the front (with PF lights).