mawashi, as far as I can see, there is no simple hack (similarly with Toshiba and Sony). There needs to be a firmware upgrade or a 'chipped remote' (see below) - but there are potential problems such a messing up your unit. As these mods involve cost, I would look for a region-free 'cheapo' DVD player.
http://www.multi-region.co.uk/product_info.php ?products_id=773
Warning!
http://www.avforums.com/forums/archive/index.p hp/t-368649.html
THERE IS NO WAY TO HACK A PANASONIC FROM THE UNITS OWN REMOTE UNLESS YOU HAVE ALTERED THE PLAYERS FIRMWARE USING A HACKED FIRMWARE CDR SUCH AS THOSE RELEASED BY VIRUS FOR THOSE VERY FEW MODELS.
By far the easiest and safest option remains a chipped remote for all other models , you could try to send the signals in this thread using a Palm pilot or Pocket PC but of course this is at your own risk as sending only 10 of the 12 commands seems to have only been tried on the units with hacked firmware.
Outlets for Chipped Remotes include ...
www.multiregionupgrades.com ( Forum Sponsor )
www.dvdchips.co.uk
www.multiregion.co.uk
www.multidvd.co.uk