This instructable will only work with some phones, because you can't imitate the most plugs that are used to charger mobile phones, but with my Sony Ericsson it works fine because of the way the phone is charged.
To find the pinout of your phone, you could use Google
, or use ( the one I used, with help of google Pinouts
). Hit Ctrl + F and go look for you phone pinout. If you can't find it, you'll have a problem and won't be able to continue, but you usually will.
My phone has a 'standard ?' Sony Ericsson plug so it was easy to find. I used the image below, disgarding the Datacable part,... which it think can be pretty usefull :).