tluck, this is not related to the t420 but would this bogus id work for a HD 4000?
i am traveling this week and will not have access to my T420 to test the installer.
one thing you could do to get the installer past any graphics issues is to inject a bogus id.
boot up the clover - but go to the Options menu (hit arrow)
then in the graphics section, change device ID from 0x0000 to 0x12345678
this will boot in non HD3000 mode..
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