Adding special moves input commands ? (as3)

I was wondering how you could accept inputs in AS3 for something as simple as making a character dash forward, to making them throw a fireball.

Example: Classic arcade beatem up: tapping forward, forward (right, right or left, left, on the keyboard) would make the character run as long as you held the second forward input in.

Example 2: Throwing a fireball in Street Fighter: pressing left, down, right, punch.

I do not know how to accept these inputs. What would you do in this situation? Create a timer and an array with the inputs that were entered and then if they meet the movements that are needed to perform the special, perform the special?

Any insight is welcome.