A regulated voltage doesn't change value, since the Wireless controller runs on batteries the best source for power is directly from them, and since they're batteries they're always getting lower and lower in value. There are regulated voltages in the controller, but they are lower than the battery value and really of no use for trying to light up any LEDs. As most Blue, White and some Green LEDs need around 3v or so to work (Red and Yellow are around 2.2v~2.7v) the best place to get power from is the batteries directly if ya want to even get them to work half decent. But there you're limited to what they provide power wise, so lighting up a Wireless controller without some external help isn't really the best idea. It can be done, but to the level ya can do a Wired controller where ya can get a nice 5v that's from the 360 it's no comparison, the Wired controller will look better every time.
Some things that can be done if one wants to light up the Wireless controller properly are to use the voltage from the PnC connector. It's 5v from the 360, same as a Wired controller, but your LEDs would only work when it was plugged into the 360 and charging or just left plugged up, essentially turning it into a Wired controller if ya wanted to play it with it lit all up and then they'd go out when it was unplugged.
Another thing is to install a DC-DC converter to get a nice regulated 5v from the batteries and drive the LEDs with that, though it's a bit more complex to do and ya could loose a Rumble motor in the process of installing it because of space restrictions.
