The Proper Equipment
Purchase a female to male USB connector. They are located at many different electronics stores, as well as many all-in-one locations.
Preparation
Disconnect any USB cable you might have connected to your computer or Sony PSP. Only use the USB cables that you are currently not using.
Connecting the Cables
Connect one of the USB cables to the female to male USB connectors. Connect the other side of the connector to the opposite side of the other USB cable.
Connecting to the PSP
Connect the USB cable to your Sony PSP and you will have made your own USB cable extension for the PSP. You can now use your PSP with your computer or PS3 a little more comfortably.