Interesting article on making your own USB Charger using a 9v battery. Should trickle charge your treo 1-2 times (not sure if would charge from full dead..hmm)
http://www.hackaday.com/entry/1234000520028239/

Comments recommend this voltage regulator instead of the zinner diode. Did a search at Radio Shack.
http://makeashorterlink.com/?R262124BA