I just figured out something, so why not post it.
This 8-Way Movement system is pretty easy actually. Just set up two Parallel Process Events that look like this:
And there you go. Instant 8 Way System.
For those of you who don't know what an 8 Way System is, it's where the player can move diagonally if they press up+left, down+left, up+right, or down+right, which makes them go diagonal in that direction.