SundanceUK

The gauges have to be prized open. Also its a good idea to check the polarity of the connections to the led's as you have to solder them on the correct way round. If I remember correctly, they will be standard 3 volt LED's not 12 volt as you would put in your dashboard instruments and switches.
Suggest you buy a couple of second hand ones to butcher, then you can always revert back to normal if you want to sell the car on as original.

Sundance