I just tried to swap an '02 Mini Cooper digital clock with my Infiniti clock. I got it to work, but the Mini clock was too orange, and the Infiniti dash lights were more of an amber color. Also, the electronics didn't integrate perfectly, to do it right you would did a driver circuit, and it just wasn't worth my time for a clock that wasn't going to match up perfectly.
The thing that really sucks is the fact that the LCD screen on the Mini clock is actually tinted, so that is where the orange color comes from. The back lighting is actually amber, but once it hits the tint it darkens it to orange. The tint is sandwiched between two pieces of glass and I didn't want to destroy my Mini clock to try and take the tint off. I posted some pics on G35driver.com (which is down now). I did a lot of serching and I found a company that makes an amber automotive clock but they are in Turkey. I emailed them requesting a sample and we'll have to see if it ever shows up.
Kevin
www.KPtechnologies.net