Has anybody ever installed [colored / indiglo] needles on a [DSM]?

Many people have done this. It is not difficult to do. The process is essentially the same as installing white faces, described above.

Converting the stock needles to a different color simply involves scraping the orange paint off of the bottom of the needles. They can then be repainted in any color. The backlighting color may also be changed. There is a VFAQ on the process here; also try the results of this Google search.