Actually, you can totally do this! The trick is just understanding how SNES understands diagonals: it doesn't. Instead of diagonals, SNES recognizes any two adjacent directions, held together, as a diagonal. So what you might think of as a down/left diagonal is really just pressing down and left together. Note: you cannot press up/down or left/right together.
Next you just have to understand the KEY COMB editor under MISC in zSNES, namely press vs release and delays. So for example, let's try a simple Haduken (from the left, shooting right). Normally we think of this as down, down/right diagonal, right, punch. But remember there are no diagonals. So here's what your hand would do to execute this move:
- Press down
- Press right while still holding down
- Release down, now only holding right
- Release right
- Punch
Then you just have to put a frame delay in. I figured this out for Sabin's blitz moves in FF3/6, but since his Aurabolt is just a Haduken, it should work for Street Fighter or any other game.
So here it is:
KEY:
P = Press
R = Release
2F = 2 frame delay
P down, 2F, P right, 2F, R down, 2F, punch
Actually, if I recall I think Haduken is simple enough to get off with:
P down, 2F, P right, 2F, punch
But that whole press and release trick worked for more complex moves like half circle. You can even set it up to make left or right be whatever was pressed last so it works no matter what direction you're facing.