Just got my boost gauge installed this morning. Bought an Autometer Z-Aeries one in black from Real Steel, along with a 4 quid pedestal mount off ebay.

Tapped it into the FPR line which I know isn't perfect, but it seems to work OK.

Pics:

Found that the best palce to wire the illumination was the back of the lightswitch, where you need to connect your positive the grey and blue wire, and connect the negative to an earth. I used the brown wire on the lightswitch.

Nice neat job