[lime-users] How to add libremesh repo to existing openwrt router?

Please can someone tell me how to add the LibreMesh repo for opkg to an existing OpenWrt router? I've tried adding the lines to /etc/opkg/customfeeds.conf, but when I run opkg update the signatures fail: ------ root@LEDE:/etc# opkg update Downloading http://repo.libremesh.org/current/packages/mips_24kc/libremesh/Packages.gz Updated list of available packages in /var/opkg-lists/libremesh Downloading http://repo.libremesh.org/current/packages/mips_24kc/libremesh/Packages.sig Signature check failed. Remove wrong Signature file. ------ I think I'm missing LibreMesh keys from /etc/opkg/keys, but I can't seem to find them anywhere. I had to build a very basic firmware image using Chef for the TP-Link MR3020, so that I could use 'extroot', which is why I think I don't have any LibreMesh keys on my router? Many thanks -Kevin