Edit build.sh so that KERNEL_SOURCES points at the extracted kernel sources
from LGP880(X3)_Android_ICS_V10a.zip.
It can be downloaded from:
http://www.lg.com/lgecs.downloadFile.ldwf?OPENSOURCE_FILE_NAME=LGP880%28X3%29_Android_ICS_V10a.zip&OPENSOURCE_ORIGINAL_NAME=opensourceWWZ%2FLGP880%28X3%29_Android_ICS_V10a.zip&detailCustomerModelCode=LGP880&DownFileType=opensource

Run as root on phone:
echo 1-0036 >/sys/bus/i2c/drivers/lm3533_bl/unbind
insmod lm3533_bl_custom.ko
#echo 1-0036 >/sys/bus/i2c/drivers/lm3533_bl_custom/bind

These sysfs files should be owned by 1000:1001 (system:radio).

Change (fine) brightness via (found in lights.x3.so):
/sys/class/leds/lcd-backlight/brightness
0..255

Change (coarse) brightness via:
/sys/devices/platform/tegra-i2c.1/i2c-1/1-0036/lm3533_bl_maxcurrent
0..19

According to the datasheet it can go up to 31 (29.8 mA), but there is are risks
to going higher than the default of 19 (20.2 mA).
I can think of backlight burning out (unlikely), overheating of LCD or other
components, etc.
You can disable the check in the source code if you dare.
Please report back with your results. :)

This module was primarily intended for LOWERING the brightness for use in bed.