Use update-alternatives to change the xinput setting so that can use SCIM in en_GB enviroment.
# update-alternatives –install /etc/X11/xinit/xinput.d/en_GB xinput-en_GB /etc/X11/xinit/xinput.d/scim-anthy 60
# update-alternatives –install /etc/X11/xinit/xinput.d/en_GB xinput-en_GB /etc/X11/xinit/xinput.d/scim-canna 50
# update-alternatives –install /etc/X11/xinit/xinput.d/en_GB xinput-en_GB /etc/X11/xinit/xinput.d/scim-prime 50
# update-alternatives –install /etc/X11/xinit/xinput.d/en_GB xinput-en_GB /etc/X11/xinit/xinput.d/scim-skk 50
# update-alternatives –install /etc/X11/xinit/xinput.d/en_GB xinput-en_GB /etc/X11/xinit/xinput.d/none 10