To do a Rocket Makio you must be able to do a Makio. You approach the grinding utensil the same way you would for a makio but you have to be more crouched down. What is hard about this grind is that you must swing your foot up and grab it while the other foot is locking in to soul. The trick to this is to have the souling foot just hit the utensil as your grabbed foot is swinging up. This will be hard if you don't step on one foot at a time and you don't want to do that because the can just hurt you in the future. This grind just take a lot of practice to master but it will come. Just practice stalling it first as you should with every grind and slowly work your way up.