I also went with loop on the fork blade and a hole (3 mm) on the DT lug. I brazed a little elbowed tube in the hole to reinforce it and to help guide the cable (it's still a PAIN to fish it through!)

I agree it would be hard to fish a wire in the fork through new holes. I think the proper way is to braze a tube like for rear brake routing, as you are building the fork.