I think he exposed a little of his praying routines in a text titled Accord with the totality of the Universe (Aikidojournal aritcle). And Hikitsuchi sensei definitely stated that chinkonkishin no ho (
http://www.cs.ualberta.ca/~mckellar/aiki/1999/0.html ) was transmitted to him by O Sensei and was a daily practice of his.