Instead, just play your DVDs using VLC. It just ignores region encoding, letting you play whatever DVD you like (it works this way with the PC version, too, in case you have one of those in addition to your Mac). It has a number of other nice features, like letting you skip previously-unskippable parts of DVDs ... and you can even take screenshots.
The only tiny problem with this is that Apple's DVD player will try to automatically load and make you change the region when you insert an out-of-region DVD. If you quit it, it will eject the DVD. You can either force-quit it, or for a more long-term solution, go into System Preferences -> CDs & DVDs, and disable auto-loading it when you run DVDs.

