You can't change the code on the DVD but you might be able to change the player to make it 'multi-region'.
Most DVD players are manufactured with 'multi-region' capability but are then encoded so that they'll only work in one particular region. Removing the encoding is usually as simple as (for example) opening the drawer, typing in a 4-digit number on the handset and pressing 'OK'. All you need is the relevant number. To find that, try here:
http://www.videohelp.com/dvdhacks
or here:
http://www.dvdcodes.net/
Chris