The Fantastic Rocking Horse - karmasutra sex position
In the Rocking Horse sex position he sits cross-legged and leans back supporting himself with both arms behind him. She kneels over his lap hugging him with her thighs and lowers herself down. She can then determine the speed and depth of penetration.
It may be easier to maintain the Rocking Horse sex position for the man to lean against a wall or the edge of the bed and help her bounce up and down or just cop a feel while she does all the hard work.