Heres one link to a guy that did a LOT of work.
http://kansaspinball.com/dmdmod.htm
I am just talking about the red tail-lights and maybe lighting the drive in sign ( solid - not flashing )
Curious as to where I would 'power' it all up to so that they were on solid when the game was turned on 
i use the regulated 5 volts or 12 volts off the power supply (the quantity & colur of the leds will determine what voltage & what value resistor or resistors you use and how many you will wire in series )
just let me know how many leds you intend using and what colour and i will draw you up a diagram with resistor values and where to connect them. 
Great offer Beaky - thanks - I will come back here with that info over the next couple of days.
Cheers
one more question, are you using the 5mm leds or the 2.5mm leds?
