I don't think it was necessary, he may have just used Susano to enhance the way it works. hmm But I think the jutsu is initially a Rinnegan technique as it's so similar to Chibaku Tensei with additional usage of Bansho Tennin. :eww:Madara's Susano'o was necessary to form the giant handseals, therefore it's both.
Maybe it pulled matter from out of space, which was from a meteor and attached the matter to a gravitational core.
Chibaku Tensei Pulls Matter to the Core
Tengai Shinsei Pulls a Meteor from Space
Probably have to unlock Rinnegan to use it. So people who implanted it cant if pain used it it would have been GG naruto
Also this^ ....gg thread/Madara only used the Susanoo to help him form the seals, speeding it up! Madara could have done it w/o susanoo but it would have took longer. So its a Rinnegan tech, sped up with MS