I tried following the vyos wiki Pimd page with 1.1.8. This failed since 1.1.8 is based on too old of a debian version without pimd packages available.
I then upgraded to 1.2.0-rc3, I added the deb source for jessie-backports, but the pimd package conflicts with Vyos's frr package due to the pimd manpage being present in frr.
I'd recommend absorbing the full frr, which includes pimd, so the functionality is available if necessary out of the box.