Some more quick tips for Japanese input methods with OS X. This works for 10.4, 10.5. Probably works for 10.3 as well, but I haven't verified this. Note that in OS X 10.5, there is a fair amount of (Japanese) Koeteri input method help in English accessible by choosing 'Koeteri Help' in the Input menu. In previous systems (10.4 and older), this help was only available in Japanese. Now for the tips...
If you type something in Japanese using Romaji input (big 'A' selected in the input menu droplet) and while the input still has a dark black underline (i.e. turn on Romaji input: Command-Space (must be changed from Spotlight's default)), you can switch modes between katakana, hiragana, expanded roman characters, and roman characters by holding down Option-Tab. Thus, typing in a phrase while in Japanese mode, the katakana version of the English word 'support' (i.e. Apple Support -- sapo-to), you can change modes as long as the text is underlined:
- さぽーと (hiragana input)
- サポート (katakana)
- SAPO−TO (expanded roman)
- SAPO-TO (condensed roman)
If holding down Option-Tab to switch between the modes is too tedious, you can also use:
- Control-K to go to katakana
- Control-L to full width romaji
- Control-; to romaji
- Control-J to hiragana
If you want a list of possible conversions, you can highlight the kanji and then do Control-Shift-R: 私は highlighted and then Control-Shift-R shows a pop-up list which will include choices such as ワタシは.
Other tricks for Japanese input: Any punctuation typed while inputing Japanese will cause the Koeteri input method to try and generate the appropriate Kanji/Japanese characters. In 10.5, if the primary language is English, you can also use Koeteri's auto-input function for frequently-used kanji when it prompts the user (in English) in a superscript for commonly-used kanji phrases. In 10.4 and older systems, this function is available but in Japanese prompts.

