recommendation for ceiling mounts for RM705 series

cadpepg1

I have a prewired home for a 6.1 set up. I bought the RM 705 speaker series system (I know it's 5.1) I want to mount them to the ceiling - any recommendations for what works best? Also wondering about the front center speaker. It's also wired in the ceiling, but would I be better off putting it under the tv? Or, how could I mount that to the ceiling too?
Thanks for any help!
RM 705 series system
Onkyo tx sr606 receiver