My initial blog dates from may 15th and this is a followup showing in a bit more detail how I did it.  I also published it on Yahoo Steel Group, but I prefer MRH which is much more simple to do.

I started off by searching for the right led in the smallest size (3.6x2.8 mm). Result: a led with a light emittance of 900 mcd (=Iv), If = 50 mA max and Uf = 2.1 V, yellow. Manufacturer Dominant, SMD led PLCC2.

I am modeling in HO. Currently experimenting with using leds to simulate the flow of hot liquid in a cast house.
 The results thus far are shown in the pictures.