The Sony PlayStation Portable (PSP) has been released in different variations since the original in 2005. The PSP 3000 was released in 2008 with a few alterations compared with the PSP 1000. The main difference was the 3000's inability to use a Pandora battery to install custom firmware, also known as "chipping" your PSP. However, you can install custom firmware on the PSP 3000-- and the method, called a Chickhen enabler, is actually easier than using a Pandora battery. It enables the use of custom firmware features while still running official firmware.
Download the PSP 3000 Chickhen installer for your PSP memory stick (see Resources). Connect your PSP to your computer with the USB cable.
Run the installer with the PSP 3000 connected to your computer. The program will erase your memory stick and install the appropriate files and folders to the memory stick. Press the "O" button to disconnect the PSP 3000 from the computer.
Select the "Photo" icon on your PSP 3000 menu and select "Memory Stick" from the next menu that appears. You will see the "Chickhen" set of images.
Select the last chickhen image on the bottom of the list. Your PSP's screen will go black and reboot itself. When it turns back on, you will be running custom firmware and be able to run home brew games.
This process is legal, but will void your warranty.