I couldn't find one for your model but found one for the DF-8150P. Maybe that'll work.
1. Press the Setup button on your remote control
2. Using your remote control, select the System Info option from the onscreen menu
3. Press the 1 button on your remote control
4. Press the 1 button on your remote control
5. Press the 0 button on your remote control
6. Press the 1 button on your remote control
7. The currently selected region should appear on the onscreen display
8. Press the 1 button on your remote control for region 1, the 2 button for region 2, and so on, or the 0 button for multi-region playback
Edit: [ame="http://www.amazon.co.uk/gp/feature.html?ie=UTF8&docId=1000032193"]This[/ame] might also help.