Please read the author notes, shown below the picture:

Hi this is a theme flasher it can flash the following files:
01-12.bmp
topmenu_plugin.rco
opening_plugin.rco
GAMEBOOT.PMF
System_PLugin_bg.rco
System_PLugin_fg.rco
System_PLugin.rco
Game_Plugin.rco
Photo_Plugin.rco
Impose_plugin.rco
ltn0.pg

while loading it automatically backup:
01-12.bmp
topmenu_plugin.rco
opening_plugin.rco
GAMEBOOT.PMF
System_PLugin_bg.rco
System_PLugin_fg.rco
System_PLugin.rco
Game_Plugin.rco
Photo_Plugin.rco
Impose_plugin.rco
ltn0.pg
to ms0:/theme folder if u don’t have that folder Make one

****WARNING****
If You Don’t Know What Flash0 is I don’t Recommend You Use This Program. It Can partially or PERMANENTLY brick Your PSP. I don’t take responsibilities if something wrong happened to your PSP.

*update*
THIS IS ONLY FOR 3.XX OE users!
IF you are in 3.10OE Please DO NOT touch the topmenu_plugin.rco or IT WILL BRICK YOUR PSP! GUARANTEED!

****Copyright Policy****

You Cannot COPY,MODIFY,REPRODUCE THIS Program Without Permission.

—-USAGE—-
put the ThemeFlasher and ThemeFlasher% in ms0:/psp/game150

Put all you Theme(rcos,bmp,ltn0.pgf) Files in ms0:/theme folder

*new*
press select to take a screenshot

—-UPDATES—-
Added arrows
Added Exit button Bug
Added new screenshot
Added screenshot mod
*new*
added usb enable and disable option:)
added firmware check(it only checks if u r in 1.5, then if you are in 1.5 it will go back to XMB)

—-TO DO—-
sounds

http://www.neoflash.com/forum/index.php/topic,3892.0.html