I want to make a little battery-powered portable phone charger (maybe 9V).

I have seen similar USB powered battery chargers such as the [Mintyboost](http://www.ladyada.net/make/mintyboost/).

My phone is the HTC Hero. Would the design be basically be the same? Except instead of USB I'd use a mini-USB perhaps? I believe the charger is a standard mini-USB.