Felipe: I have not installed it on a Mac, but I would believe that there are decent installation instrucations for at least python and wxPython. pyXML should be installaed in the python/site-packages directory I belive, but I think that at least the Windows version took care of that by itself.
Matias: Do you get any errors? To run Mattricks you would type : python mattricks.py
Please also check:
http://lists.lysator.liu.se/pipermail/mattricks/2004-July/000442.html
Note that you should try and use wxPython 2.4.2.4 for now as the 2.5.* are still not supported.
I'll try to get hold of an OS-X-machine at some stage to try and see if I can actually learn how to do it and create an installable bundle. So for we've had reports of people being able to run it and it should be possible.
/Oscar