I actually used two different colors. The bulbs behind the gauges are blue while the ones in the clock and odometer are actually white. I got the "how to" from another forum: http://www.sl-i.net/FORUM/viewtopic.php?f=8&t=14157
The bulbs came from superbrightLEDs.com (I think that's right) and are
# T1.5xHP - for the clock / odometer
# WLED-x5 - for the gauges
These are non-polorized so you won't have to worry about installing them backwards and then having to open it all up again.