Do you have to use your script - far more efficient would be something along the lines of...

1. Put the file on a file system on a local host that is/can be exported (via NFS) to all intended remote client machines (to save copying time)
2. NFS mount(1M) the exported file system on each remote client machine
3. Run the install on each remote client machine

The latter 2 steps could be achieved in parallel, in sh(1), in a manner similar to...

for M in M1 ... Mn ; do
    rsh $M "nohup mount <source mc>:/<export fs> /import/fs ; /<import
+ fs>/install " &
done
[download]

I'm inferring that, since you have permissions to install on the remote machines, you have permissions to run mount(1M) - and to create the mount point(s) on the remote client machines (if needed).