er... well i really only know the basics.
In the middle of a combo, you do a 90 degree shift by doing say facing 6
(combo) 33 A 99 AAAA (combo)
I've only seen it done, but I don't really know HOW to do it mid-combo. And the first A is supposed to miss, the last 4 A's are supposed to hit.
And for S cancel its like
Dash A AAAA S(walk) AAAA combo combo
S to cancel some stuff since it's dash cancellable, but costs HP