How to override ChipID for R300 (Softmod)?

[Stefan B.]

Hallo,
i want to override the DeviceID of an Ati Radeon 9500 (R300) to get one
more quadpipe (Softmod). I added 'ChipID 0x4e45' into 'Section "Device"'
that doesn't have any effect. The 'Xorg.0.log' still shows 0x4144 ChipID.

On MS-Windows i patch the driver on binary level by swapping the IDs
that works flawlessly. I also tried that on Linux 'radeon_drv.so' but it
doesn't have any effect. Performance is tested with 'glxgears' resulting
in ~2600fps always.

Any idea why the ChipID override doesn't work by X configuration?

20-monitor.conf:
http://pastebin.com/SPahTfAb

Xorg.0.log:
http://pastebin.com/tDd903mX