This one below apparently works for quite a few of the Memorex models, so it has to be worth a go:
1. Open the disc tray
2. Press CLEAR
3. Press 1, 3, 6, 9
4. Enter region (0 = multi-region)
5. Close the disc tray
6. Power off
I`ve not tried it but it would be useful to others if you post below as to whether it works or not :)