As that is a Swyama Siddha Hanuman Mantra it doesn't have being chanted for a set variety of Mantra Repetitions for being able to use it. Particular worship and rituals and procedures relating to way, sitting down mat, and counting rosary are usually not proposed for chanting this Hanuman Mantra. https://www.youtube.com/watch?v=ufkmD95y7fE&t=32s