Doom3 engine self shadowing - how do I turn it off?

[Geebs]

Seeing as doom3 discussion has disappeared, I thought I'd try in here

I've been using the GTX mod because, frankly, it makes the default renderer look like a murky POS. However, they do insist on self shadowing on the models, which looks rubbish and doesn't help performance. How do I turn the self shadows back off again?