How to enter special symbols with Alt in Emacs under Mac Os X?

In Mac Os X using the alt key with some other key will produce a series of special symbols. E.g. alt-' results in æ, alt-3 results in £, etc. When using emacs, however, I can no longer input these special symbols this way since alt is now mapped to meta. Is there a way to map alt to some other key combo? Or maybe use the left alt as meta only and have the right behave as it normally does in other apps?