I don't think it's changeable without a mod... if you just don't want to type in the codes all the time, write a bind (this one's for singleplayer).
bind xkey "helpusobi 1; setforceall 5; setmindtrick 3; helpusobi 0;"
should do it (I think; it's been a while since I played it). xkey is the key name you want to replace.
Tavion's style is fast as normal blue, but does more damage and I don't think it has the lunge move. Desann's red style moves much much faster than the normal red and allows you to combo more attacks, but I don't think it has the DFA move.
sorry for no one replying faster, but this section of the forum is pretty much deadish.
"Words are deeds." - Wittgenstein