Hammerheads and tailslide (front and back) are possible and easy to do with standart FM, I can do it so you can do it.. with su33 or su27 with no problems...
just enter a full stall using some full left rudder/stick and full elevetor(pull) untill you can pilot only with rudder, then climb up to vertical flight and add full rudder when speed is almost zero and there you'll have a kind of hammerhead...
In this kind of "advanced stall" you'll have a lot of AOA, so make sure your flight direction is vertical and not just your AOC at 90° (probably it'll be 110° )
EDIT,: pilot just with rudder and elevator, no ailerons in "advanced stall"