The fix you linked to is already applied to Irrlicht 1.5. AFAIK, the only difference between the Mac version of Irrlicht and the standard one is it comes with OSX binaries. So just download Irrlicht 1.5, open the Xcode project in /source/Irrlicht/MacOSX and recompile.
However, when the 1.5 for OSX is released it will have a couple of extra bugfixes, so stay tuned!
Edit: There are some more broken keys, a lot of characters are missing including: ', `, |, $, %, &, (, {, }, # and €.
I've added a bug to the tracker here-
https://sourceforge.net/tracker2/?func= ... tid=540676