They would probably work for the warning lamps, and look the same as what the message center is lit by
The ones that light the back of the gauges and the needles are 5W capless lamps in the bases. The only problem is how the light is distributed inside the cluster - LED's are very directional, and the standard lamps emit light 360 degrees, which is how the factory lighting works. It uses 'light pipes' to channel the light to where it's needed, which come off the side of the tungsten lamps.
All of the LED's I retrofit are all SMD and fitted to light the individual needles - and edge-light the back of the gauges and the message centre screen.
Also from the factory, the back of all the gauges and message centre have a green coating which needs to be removed if you want to get white for example - as even if you refitted with white LED's the green coating would still make everything shine green. (though blue LED's seem to come through as a shade of blue - but not the brightest from when I was playing with them.
The reason I went and edge lit everything was because just replacing the lamps with LEDs originally gave me very dim, and patchy spots of light, as the light was just shining in the cluster, and not through the light pipes to actually illuminate much. It's very clever how they've done it, but doesn't make it easy to retrofit!
