Simply download and install the MacOS drag-and-drop installer for your system from http://www.OpenMS.de .
To use TOPP as regular apps in your shell just add the following lines to your ~/.profile file. An adapt the first line to point to the folder where you installed OpenMS (e.g., /Applications/OpenMS-1.10.0)
export OPENMS_TOPP_PATH=<OpenMS-PATH>
source ${OPENMS_TOPP_PATH}/.TOPP_bash_profile
| OpenMS / TOPP release 1.10.0 | Documentation generated on Thu Mar 7 2013 09:42:47 using doxygen 1.7.1 |