Japanese IME with non American (-> Swiss) Keyboard layout?

Hi, I am trying to use the Japanese IME to type some japanese. However that seems to change the underlying keyboard layout assumed as well - with the IME I now get Z, Y, *, (, ) and other characters when pressing the keys they are normally assigned to on an American keyboard:

http://www.dtp-transit.jp/images/apple-keyboards-US-JIS.jpg

which is different from the Swiss layout:

http://upload.wikimedia.org/wikipedia/en/e/e1/Keyboard_Layout_Swiss.png

For example, in the Swiss keyboard, the * character is suppsed to be Shift+3, but in the American it's shift 8 and so with the japanese IME on, I only get it that way.

Is there some way to select the keyboard layout used with the Japanese IME? On Windows, this requires a hack (you need to tell the IME which keyboard layout dll to use via the registry), but it is at least possible:

http://nejtj.blogspot.ch/2011/09/howto-japanese-ime-with-non-japanese.html

Is there some way to get the Japanese IME on Mac to use the Swiss keyboard layout? I wouldn't bother having to manually recreate it if that was the only option, but tell me where to start.

Thanks in advance,

Paul