It depends on the type of commands you want.  If you want a command to be down-forward + 1 (not Down, then Forward), that is possible by just adding that to the Button Execution for the Move's Input.

If you want more precise control over the Sequence for the command (e.g. down-forward X 2, then Punch), then you'll need to mod in recognition for diagonal inputs.  Check AbstractInputController.cs, and anything that references it.  This isn't easy though, as there's quite a few tricky scenarios to consider.

However, we will have diagonal inputs in an update - possibly the next one.  But there's still no solid date for that yet, sorry.