There are two aspects to lighting a prop. 1 - Make it emit light, this can be done by putting a point light near or in the prop (don't forget you will have to use ray tracing and if you put a light in a prop the prop itself must not cast any shadow). An additional primitive prop (with shadow on) may be required to cast correct shadows). 2 - Make it appear to light up, this is done by setting the correct color (or map) in the ambient channel and increasing the ambient value to above 1 (in general the diffuse value should be set to 0).