Custom themes are a great way to personalize your PSP using the CXMB plugin. The only requirement is having custom firmware. Custom themes are in .CTF format and go in the /THEME/ folder on your memory card. Some themes made for older firmware won’t work or won’t show correctly on newer firmware.
Download
Download CXMB and unzip the contents. Place the cxmb folder in seplugins on your memory card. If you don’t have one, create a folder on the root of the memory card.
In the seplugins folder open VSH.txt or create a new text file if you are missing it. Add the following line depending on what model your PSP is.
If your PSP has a UMD drive put this line:
ms0:/seplugins/cxmb/cxmb.prx 1
If you have a PSP Go use this line:
ef0:/seplugins/cxmb/cxmb.prx 1
Save your changes and disconnect from USB mode or put the memory card back into the PSP. Reset the VSH or reboot. While this plugin is active your themes listed in the settings menu will only show CTF files. To change this just disable the plugin in the recovery menu by pressing select on the XMB.
Check out some themes you can try: PSP Themes