You must set the environment variables:
PVM_ROOT to /usr/pkg
PVM_ARCH to NETBSD

in your startup files (.cshrc, .profile) on all machines
in the cluster.

In addition, you can specify each host's run path in your pvmhosts file
like so:
hostname ep=/usr/pkg/bin
This allows you to point different achitecture types to various sets of
shared or local binaries.