Filing this away for future reference.
Install munin from package sources
apt-get install munin-node
Add master node to allowed IPs
Unfortunately it's only allowed to add IPs and not hostname. The format you'll have to follow is:
Clone the official plugin repository
We are going to clone the repository with the latest third-party plugins to
/etc/munin/plugins-get. Once you've done this just symlink the plugins you want to use into Munin's plugin directory. This also makes it very easy to update.
git clone https://github.com/munin-monitoring/contrib.git /etc/munin/plugins-git
In this example we are going to symlink a plugin which accepts an additional parameter. In our case the network interface on this OpenVZ server.
ln -s /etc/munin/plugins-git/plugins/network/vnstat_ /etc/munin/plugins/vnstat_venet0