This is a simple init.d script for permanent disabling hardkeys backlight on any desire rom, without additional software.
Just
rename 54DisableKeybLight.txt in 54DisableKeybLight
adb push 54DisableKeybLight /system/etc/init.d/
adb shell chmod 755 /system/etc/init.d/54DisableKeybLight
OR
flash zip
Just
rename 54DisableKeybLight.txt in 54DisableKeybLight
adb push 54DisableKeybLight /system/etc/init.d/
adb shell chmod 755 /system/etc/init.d/54DisableKeybLight
OR
flash zip