The download area is at :
http://pmx.lal.in2p3.fr/download
Here can be found various binary kits but also some example data files.
pmx is available on the AppStore since the January 2012.
pmx is available on the Android Market for devices with at least Android-2.0. Note that the pmx-release.apk is also available from the download area.
On a Mac, download and unzip the pmx.app.zip, then click on the pmx icon (or do : open pmx.app, from a terminal). Remember that data files are searched within the directory :
~/Documents/pmx