The problem is that LED's are effectively not adjustable with regard to their light output because the MB interior lighting circuitry is voltage variable not current variable. The circuitry for the interior lighting varies the voltage levels to achieve dimming effect with incandesant bulbs. LED's have a threshold voltage and either turn on if it is exceeded and turn off it is not. An LED's brightness is affected by the flow of current to it.

Another potential issue would be the positioning of the LED, most LED's are not omni directional in the orientation of their light output. Usually there is essentially a "primary cone of light output" that could require a specific placement of the LED to maximize its ability to illuminate the entire display area.