there does not seem to be a hack for the 105 but this hack is reported to work on the 105 but is for the 205 but if you have a 105 with the later firmware its surposed to work
"If you have a player with newer firmware i.e. 5.02E try this:
Power on your player
Press and hold both the Play and Stop buttons
on the player itself
After a short while you should be presented with a
set of language options. Release the play and the
stop buttons on the player
You will now need to select a language option
between 1 and 6
Press the Repeat button on your Remote Control
Now using your Remote Control enter the code below,
note that you must know what Region your player is
currently set to in order to know which code is
appropriate, for Region 2 use 5, 7, 5, 3, 8 instead of 3, 8, 7, 6, 7
A code should be displayed on the screen indicating the current Region setting of your unit
Press the 9 button on your Remote for Region free, or press 1 button for Region 1, button 2 for Region 2 and so on
Press the Open button on your player
Press the Standby button on your Remote Control