I'm stumped.
What bios version do you have in your DX?
I just did the follow on my machine to verify:
1. Insert iBoot CD
2. Boot machiine from iBoot CD
3. Eject iBoot CD when the Chimera screen shows
4. Insert Snow Leopard DVD - wait a bit hit F5 a few times
5. Select/Highlight the Snow Leopard DVD in the Chimera menu using the arrow keys
6. Type GraphicsEnabler=Nö and hit enter
7. Wait...apple loga comes on screen with spinning thingie....wait wait wait wait....
8. Install screen shows up asking for language - job done
Is your BIOS set to ACHI?
What's your CPU?