I have a Macintosh running MacOS X 10.3.6.

The system is running in English, but I am using a Japanese keyboard. 
As a result, the keymappings are incorrect.  For example, when I hit
shift-7 on this keyboard, I should get an apostrophe, but instead get
an ampersand.

I am looking for step-by-step instructions on how to get MacOS to
properly recognize my Japanese keyboard, without having to custom
create an XML keymap by hand. 

Please note, I am _not_ looking for information on how to input
Japanese characters into MacOS.  This can be easily done by selecting
the Japanese input method.   Also, be aware that enabling the Japanese
input method and choosing "Romaji" from the International dropdown
does not cause the keymap to switch.

Thanks!

Do you use the English OS? I don't think you can change that unless
you have the Japanese OS. I know the positions of some words on the
Japanese keyboard are different. If you think differently, the
keyboard you own, it just has stickers of Japanese letters. The
positions depend on the Operating Systems, so if you use the English
OS, you better look at an English keyboard and make sure the
differences. (the position of @ should be different. on an English
keyboard, @ is shift + 2.)

I hope this helps.

It's not just a question of keys shifting -- the Japanese keyboard has extra keys.