install in /usr/local/share/munin/plugins/
run: cd /etc/munin/plugins sudo munin-node-configure --libdir=/usr/local/share/munin/plugins --suggest --shell | sudo bash
Edit the config files: vi /etc/munin/plugin-conf.d/bitcoin.conf
[bitcoind_*] user
and likewise for litecoin vi /etc/munin/plugin-conf.d/litecoin.conf
[litecoind_*] user