the ones you linked don't have any external power hookup so the light may be a bit dim since the white light goes through the green coating then blue coating. from the looks of them, the holes are small so you'll have to remove the needles and will have to recalibrate the speedo. also they are quite pricey and you can find overlays much cheaper on ebay.
i picked up these for $30 shipped on ebay
they haven't arrived yet but they look decent to me in picture though some may say cheap. they hook up to an external power source and have their own light source, so the lights will be bright. i believe the dummy lights will be the original light source just going through openings in the face plate but for the most part it will do what i want it to do. also the holes are large enough to just slide over the needles so i won't have to recalibrate anything.
if they don't do it for me i plan on going the route fx4 mentioned but i wanted to try something easy first. i'm definitely going to have to go that route for my a/c gauges so i guess i'll get practice on that if i decide to go the sport trac - sanding - painting method
anyway i hope to take pictures of the experience and make a how-to when i'm done so that should be posted monday if the overlay arrives today or tomorrow.
PS i have white needles as well so we'll see how hard it is to see white on white during the day.... i may have to take the needles off in the end and repaint them if it's too bad