What do I need to write Japanese (kanji) on my Mac?

I have a Macbook, but it's slightly too old to use Mac OS X 10.6's trackpad Chinese input.

I have a Wacom tablet, but even though Mac OS X has had tablet character recognition since 10.2 and now knows Chinese characters, they're separate enough that it apparently can't put these two together and read Chinese characters I write on my Wacom.

But I'm sure somebody has a way to let me do this. What software do I need to let me write Japanese kanji on my Wacom tablet under Mac OS X?

Tegaki is open source Chinese/Japanese handwriting recognition software that supports Mac OS X.

Support for this feature is understandably limited in the mainstream. I lived in Japan for a few years, and keyboards are far-and-away the preferred input method of native Japanese writers.