Wondering if you can replace the black outer casing of the buttons of the EF cruise control to the grey EL ones?

sure can...

buttons pop out... need to press the hinge bits in with a tool of some sort... and the tops (actual "button") comes off showing the circuit board and then the circuit board just slides out of the bottom and into a new one... Make sure you pop out the buttons in the right order... double set first and then the single button second I think... go together in a certain order is all...

I have made one good set from two broken sets before...

Be VERY careful... They are brittle as all s**t... Best leave them in the sun til they are hot and soften the plastic as much as you can... practise on a set you don't want first... Nearlyl guarantee you'll break the first set you try on...

Cheers,
Tim

Cheers Tim. I might see if I can track down an old set of black cruise control buttons and see how I go taking them apart...Hopefully I don't break them.