Hello, it might interest you to know that there are several programs to redefine keyboard layouts in both Windows and Mac OS X. While it might strike you as strange to make a custom layout just for use with PM, it makes more sense as you look at it - most software's shortcuts are made for US/International layout, which is understandable. There are already bundled better layouts with some operating systems, e.g. "Programmers" versions (which have QWERTY keyboards but still allow the national characters and have all the main [],./\ etc chars in the right place as in US/Intl keyboards). Using the software tools you can even make a keyboard layout that would have the international "programmers" characters in the "right" place (i.e. []/\ ...) but still allow you to enter national accented characters using a "dead key", the best being the right-alt (known as Alt-Graphics, or Alt-Gr key). I.e. pressing Alt-Gr + o results in accented o on my modified keyboard, while the keys most used by the system (/\:-_[]{}) are still in the same usual place as on the international/US keyboard).
Really, you should try that.
My Windows computer is down at the moment, so I don't remember the name of the software I used to create the layout, but there is also Microsoft Keyboard Layout Creator, freeware from MS to make custom layouts. And on Mac, you can try "Ukulele" which should accomplish the same.
Hope this helps, Frantisek