Sigh....
Please stop giving this kid bad advice....
These are computer Neons... and from what he has said and what i can see, they arent neons.... they are CCFL's.
There are 4 Pins on them for a reason - 12, 5 and Ground. On the pic that shows the circuit board you can see it uses all 3.
Now im assuming it uses the 5v connection for a control source. Hence it wont work with a car unless he can tap into a 5v source.
Now the ccfl uses a high voltage AC source. Hence why there are 2 WHITE wires coming out of them going to the converter. You cant supply 12v DC to it, it wont work.
Check your power source on the PC and make sure 12 5 and ground are Yellow red and black respectively.
If thats the case, you're out of luck, unless you want to see if you can splice to a 5V source anywhere in your car.... which i wouldnt reccommend because i would assume it would be used for something like the ECU... which i wouldnt want to compromise for some piddly neon glow.
Get a dc converter to get your 5v requirement, or goto Autobarn or jaycar and buy some automotive grade neons.
Ed