Roger,
Is this flat wire a type of standard jacketed-wire flat ribbon cable; or are the copper conductors themselves flat strips sandwiched in layers of flat clear plastic?
If the former, I'd suggest using punch-on sockets available from the electronics outfits, and the matching header pins soldered to the lamp leads. If the latter, I'd suggest using the 1/2" fabric pins available from your local craft store, stabbed through the ribbon wire and into the underside of the layout (to avoid the sharp end with hands later), and simply solder the lamp leads onto the heads of the pins.