Are there emulation options availble to simulate controller input for Unity?

Hey everyone,

So I'm getting to a point in development that I need to test 4 player interactions...unfortunately I'm faced with two issues. First, my laptop only has 2 USB slots. Yes, I know I can get a hub but that leads into my second issue; I'd need to carry around 4 controllers. And even if I could get 2 more PSP GO's and CFW them, that's still a good amount of hardware to carry around. So my question is this:

Does anyone know or have a solution for emulating a controller that Unity would recognize?