Windows – Typing Japanese on Windows Vista with Dvorak

I'm using Windows Vista, and I type English with the Dvorak keyboard layout, and I want to be able to type Japanese text that way, too.

I've figured out how to set it up to let me type Japanese here, but it uses QWERTY. What I've got so far is:

• click the "EN" in the taskbar, and select "JP"
• if the letter that appears in the taskbar is "A", hit alt-~ to change it to "あ"
• type as if I was typing Romaji on a QWERTY keyboard, (e.g., left pinky home row, right ring finger top row), and hiragana appear (あお)
• press spacebar to convert to kanji (e.g., 青), and return to accept

That all works great, but it assumes I'm on QWERTY, which isn't very comfortable for me. I want everything the same, but to be able to type kana with Dvorak (e.g., left pinky home row, left ring finger home row -> あお).

I can do this on Mac OS, so it's not an unheard-of feature. But it was kind of an obscure setting to find, so I figure on Windows it's probably a really obscure setting. 🙂 But I haven't been able to find it yet.

Thanks!