Hey Mike -
This modification is done by changing the surface-mounted LEDs inside of the button. It requires solder work and a very steady hand - it is not typically a DIY mod unless you're well versed in working with wiring/soldering. As for a how-to on doing that - google is your best bet. This was a "trade secret" of sorts for Surman and was never really openly discussed much further than this. Sorry we couldn't help too much further regarding that.
If you simply want the start button to be changed, one option is the GT-R start button, which you can order from any Nissan parts website. I'm not sure what color the illumination is for any Infiniti start buttons, but it is possible to order the part from any dealership. They'll run you around $50, and luckily, they're very easy to install on the Altima. Shout back if you have any other questions.
EDIT: here is the link to the GT-R button posting on our forum. There aren't any pictures, but there is a rough summary on how it's done. This is probably the easiest mod I have ever done on my car. Took me about 15 minutes.
post6032929.html?hilit=GTR%20start%20button#p6032929