If I understand correctly, you're simply trying to run 2 jobs, 4 MPI processes each, on 2 different machines - is that true?
Could you provide us with how you run your application (mpdboot/mpiexec command line, or mpirun, if you use that), as well as any mpd.hosts files, machine files, or config files, you might use. At this point, we need a bit more information to make a suggestion.
The -f option in this case would only read the names of the hosts you want to use. What you can do here is use the -perhost option, which helps you indicate how many processes the Intel MPI Library should put on each node. Your command line will look like this:
$ mpirun -f host.list -perhost 4 -np 8 /easd/apps/vendor_appl/devl/Interwell5.3/bin/Linux/csh_presti_exe
Let us know how this goes.