How to setup scim in archlinux (with gnome 3.8)

Install scim first
$ sudo pacman -S scim

And, install whatever tables you need, in my case, scim-tables is enough
$ sudo pacman -S scim-tables

Then, setup environment variables to tell applications that you are using scim. Edit ~/.xprofile, input commands below
export [email protected]=SCIM
export GTK_IM_MODULE="scim"
export QT_IM_MODULE="scim"
scim -d

Logout and login again. Open a terminal, type CTRL+space to try to activate scim...nothing happen, why? Run
$ echo $GTK_IM_MODULE
scim
$ echo $QT_IM_MODULE
scim
$ echo $XMODIFIERS
@im=ibus

ibus?! Oh~ Gnome 3.6 already into desktop environemnt, so we need to
$ gsettings set org.gnome.settings-daemon.plugins.keyboard active false

disable it