As for MPI, you can install different implementations.
Compiling and installing Mpich2 was very straightforward. The test again as for PVM should be spawning of /bin/hostname. The install guide is a great help in setting up MPICH2.
On the master (node0) you type:
mpd & mpdtrace -l
And you should get back the node name (say node0) and port number (say 51227). Then you connect each node to by typing:
mpd -h node0 -p 51227
After this, you can spawn processes with mpiexec:
mpiexec -n 10 /bin/hostname.