a Company called Lightsheet systems sells a solid sheet product called Light sheet which is basically small bendable sheets of Indiglo material.
You need a transformer to change the low voltage (3.3V in the empeg), to a higher voltage needed for the sheet to glow.

the big thing is that the sheet is cutable and bendable, so you could possibly cut the sheet into a area small enough to go under the buttons on the front panel - you'd still need to mount the transformer somewhere [inside the empeg].