Short answer: No official method exists. The PS3's DVD region lock is hardware-enforced and tied to the Blu-ray drive firmware. Unlike PS1/PS2 games (region-free on PS3) or Blu-ray movies (region-free on PS3), DVD-Video region coding remains locked to the console's region (e.g., Region 1 for USA, Region 2 for Europe/Japan).
PS3 games are region-free (except a few early titles). PS3 Blu-ray movies are region-free (mostly). Only DVD-Video and PS1/PS2 games (played via backward compatibility) enforce region locks.