Playing around with a spare decoder I fitted a LED light strip to a Dapol coach kit to see how it would work, with a view to fitting out better stock at a latter date. I made up contacts with copper clad strip and phosphor bronze strip, for the LED I used the following from Ebay
http://www.ebay.co.uk/itm/LED-WHITE-SMD-FLEXI-STRIP-150mm-LONG-DC-DCC-NEW-/120864418248?pt=UK_Trains_Railway_Models&hash=item1c2414a9c8
Project worked well I did add a thin coat of glue and glaze around the edge of the LED strip to enforce its sticking down and placed the decoder in the toilet compartment.