XMB Multi Customizer is a homebrew app for all the PSP owners out there who love tinkering with their XMB themes. The app itself has a pretty intuitive GUI and allows for a wide range of customization options for the XMB.
The developer, Takeshi, has released an update for XMB Multi Customizer that gives it support for Dark AleX's custom firmware 5.00 M33. That's the only thing added in this release. Oh, note that this app is for Windows only.