Then you need to release the instrument pod.
Starting with this
EDIT (
I've now found that with a bit of wiggling you can simply release the cowl by undoing the 4 screws and ease the cowl forward and rotate anticlockwise to get it out of the way and then remove the 4 screws holding the instrument pod. This means you don't have to remove the steering wheel
)
So, the outer cowl of the dials is held in with 4 screws, two shorter ones here
and here
and two others here
and here
You can now ease the cowl forward and rotate anticlockwise.
The instruments are also held by 4 screws, two here
and here
two here
and here
It is now possible to pull the instrument pod forward carefully.
Ease it forward to access the 4 warning light bulb holders on the right.
On my car the 3rd one down is redundant.( auto transmission fault).
(Obviously, if you have a Steptronic, you'll need to use another redundant warning light but the principle is the same.)
I removed the bulb holder.Twist to remove.
Take out the bulb and run a 5mm drill through the holder from the back.
You can now push a 5mm 12v led in from the back.
I used a pre-wired 12v 5mm blue led but the colour choice is yours. That warning position has a yellow filter on it so any colour led will work.
Because the led is setback in the holder it gives a much softer illumination to avoid heart attacks the first few times it comes on.