Link to the software in question. This removes the chance for possible confusion over what you are refering to.
Look the packages available via whatever package manager whatever distro you're using uses and check there isn't a package for it you can just select and install.
Assuming you're talking about http://sourceforge.net/projects/mpssh/
then download it, unpack it and type make in the directory that results. You don't need to 'install' it but you can copy the resulting mpssh executable anywhere you care to