That would make a really good addiction to Oblivion.
I mean a mod were you could damage enemy with the horse's strike, and it would gain strike level... So they could even attack other horse, like medieval duels.
I think they could do it.Ive played many games where controlls very depending on what your doing.Im sure if mounted combat was added when you got on whatever it is your riding they would show you the controlls.I still think you should be able to ride something that flies or atleast turn into something that can.