Thanks to Ubuntu team and also member of asus-ul30 mailing list who work together to collect DSDT from other people who have hybrid graphic cards as well and analyze them, i now able to set my brightness and disable NVidia card temporarily to boot my battery life much longer than before.
To set the brightness, you can just use xbacklight command from xbacklight package, included on Slackware's default package on x/ directory. I used this two scripts on my laptop
xbacklight -inc 10
xbacklight -dec 10
Give them light-up and light-down and put them on some place on your PATH. I used /usr/local/bin, since it's my own scripts. Don't forget to give execute permission by running chmod +x /usr/local/bin/light-*. To make it easier for you to change the brightness settings, i made a shortcut using KDE's Input Keys so that i don't have to open a terminal.
To set the default brightness everytime i started my KDE, i used this script
case $1 in
default) xbacklight -set $LCD_DEFAULT;;
up) xbacklight -inc $LCD_STEP;;
down) xbacklight -dec $LCD_STEP;;
*) xbacklight -set $LCD_DEFAULT;;
About switching off the NVidia card, you can see the script on this blog.
With these problems solved, the only things that bother me is how to use NVidia card instead of Intel. I wanted to enjoy the beautiful KDE effects on my laptop. I'm waiting for that moment to come