Hi
I've just done that in may lab. I mounted (fstab) nfs share to a local dir :
1.2.3.4:/data/nfs-pbs /mnt/nfs-pbs nfs rw,async,soft,intr,noexec 0 0
and then added it as datastore with this (absolute) path : /mnt/nfs-pbs
.. did not understand what you meant by your question at the end ...