If the mounted NFS directory is RO, you cant execute (./install)
Unmount, chmod 777 then remount and try it. Also don't mount RO.
If that doesn't do it, you may have to do a manual install from the CD or a Boot floppy and choose NFS install from that point. Sometimes it isn't posible to perform an install from a local or mounted directory. This is the case with SuSE. I'm not familiar with redhat (anymore)