I think plzbreakmycmpan did something like this a while ago. http://www.giantitp.com/forums/showthread.php?t=142554 But does not get much in the way of special mount goodies.
Maybe you could work out something nice by combining druid, prestige paladin and arcane hierophant along with halfling outrider.
Quite right my good man, though the spelling on the name is
(PBMC is fine). I took the ubermount idea and
optimized it as far as it is ever possible to go. So consider this one of my areas of expertise.
Hijaxx you will really save some time by reading my work. I think I even put in notes about why prestige pally and halfling outrider aren't optimal. Also keep in mind that the +nat gains don't carry over from AH and many of the abilities gained from animal companion, special mount, and familiar are obscelete (the overlap / don't stack)
You may PM me if you like.