This instructable will teach you how to put custom cxmb themes to a psp with cfw 3.90 m33-3.
These will make you're old themes unusable so delete it or make a copy.
Step 1: Download This 2 Files.
Step 2: Extract
After you have downloaded the 2 files extract the cxmb file anywhere in youre computer. In the cxmb folder there must be 3 files. Then put the cxmb folder on the main folder of your mem stick.
Then extract the theme to youre msO:/PSP/Theme. I didn't put all of my themes because it's over 800mb.
Step 3: Enabling the Plugin
Turn off fully you're PSP then open it at the same time holding the "R" button to access the Recovery Menu. Then under Plugins activate the cxmb.prx.
Step 4: Change You're Theme.
You're done! If you want more themes search carefully for what is only compatible with your cfw because you may brick you're PSP. And don't frequently change you're theme or put another mem stick without the cxmb and the theme.