Unsure of permissions when installing piSNMP.
When installing piSNMP the inegration does not strictly have to be done as root however, this is recommended as it is required for the older versions and the installer upgrade wouldn't be able to overwrite those files if it didn't.
The latest tarball needs to be installed as root but the default config file that gets copied to $PPHOME/cfg/piSNMPpoll.cfg is chown'd to ppadmin. Copy this to $PPHOME/cfg/MCNAME.cfg for each piSNMPpoll message channel that you create, where MCNAME is the name of the message channel.
The latest documentation for piSNMP can be found here: https://netnow.jira.com/wiki/display/piSNMPpoll/piSNMPpoll+-+v1.0.x