I'm kind of surprised no one has done a demi-god level OSR clone. I personally LOVE Creation as presented in Exalted 1e. I really wish a legal hack of it to D&D could be published. The hard part would be making it relatively rules-lite, similar to BFRPG, but I think it could be done.
Have the "classes" actually be the Caste. You wouldn't be a Fighter, you'd be a Dawn Caste. I'd add in Feats of some kind. Nothing too crazy, but one special ability every few levels would be fine.
Starting hit points, number of attacks, etc., would all be equal to level 10 or so. Yes, the character would plow through your typical goblin mob, but that's the point. They'd be far more interested in finding the local big bad and taking him down, than wasting time killing a few bandits. Then again, if they wanted to kill the local bandits, they'd do it in an hour or so.
The hardest part would be keeping the game interesting, but the same problem exists with normal high-level D&D. Starting there would be ok, by me.
(Hmm, one idea would be using the high-level character creation rules from the Companion rules).