The two color is easy. there is a center LED that shines into the needle.
If you take a picture and mark the LEDS clearly, you will see them circle in a sea-shell shape sorta. you will see two lines, one for each of the colors (ie, one for the numbers and one for the dashes).
He is using bright white and blue LEDS.
That picture is from another forum, I suggest you check the thread. He has detailed instructions on it.
If you have someone who's going to do it, make sure they are competent enough to do it. No offense, but just because they are "willing" doesn't mean its an easy job. I have been sodering for years and years and this job has still been a b****.
Let me make a suggestion, get the thin soder and use flux. keep some paper towels around and a nice wet (but squeezed) sponge around for this job.
You should also make sure you test out the first LED to make sure it works properly and make sure you soder them in the correct way or this won't work.
goodluck! post pictures! and try doing different colors rather than doing something someone else did!