Since I'm playing with the kernel framebuffer and openchrome graphics drivers for the VIA integrated graphics chipsets right now, I have a somewhat of a de-ja-vue.
In order to access the GPIO ports that are used for I2C/DDC, you need to use 8-bit I/O read/write to an indexed VGA register. You write the register number to 0x3c4 and you can read/write the actual data from/to 0x3c5.
This remembers me of the 1991 to 1993 time frame, when I was a teenager peeking and poking the registers of my then brand-new VGA card from turbo pascal programs on DOS.
I cannot believe that this kind of legacy is still around, in hardware that is produced 2009 :)