I'm running a Nov 2009 version of current in a laptop with an Sis 630 video chip. When I first bought the laptop I struggled mightly with the video and found this resource.
http://www.winischhofer.net/linuxsispart1.shtml
On the second page there are some example xorg.conf files that you may be able to tweak.
http://www.winischhofer.net/linuxsis...shtml#download