thold

I used my notes from here to install PIA. then got a copy of thold from the Cacti plugins page.  There seem to be a lot of links to useless Cacti plugins this one appears to be updated regularly.
wget http://docs.cacti.net/_media/plugin:thold-v0.4.9-3.tgz
tar -zxvf thold-v0.4.9-3.tgz

cp -R thold /usr/share/cacti/site/plugins/
It might be easier to just copy the file to the plugins directory and uncompress it there.
Since this is a newer version of plugin just enter the web interface and enable the plugin there.

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All done.
This requires the settings plugin but setup is exactly the same as this.