Building a new retro gaming computer -- Atari 2600 question

Hi there,

I am in the process of building a computer for retro gaming.  The computer will be using Maximus Arcade for the frontend, will have HDMI out and will emulate the following systems -- Atari 2600, Intellivision, ColecoVision, Neo Geo, Nintendo 64, NES, SNES, Sega Genesis and TurboGrafX.  The case will be a gutted NES system.  I don't want to hook up a keyboard/mouse to the console, and want to use only original controllers to play each system.

The first system I am setting up is the 2600.  The 2600 has a few switches on the actual console, and my question is how can I emulate those switches without a keyboard/mouse?  Is there anyway I can do it through the controller itself -- or is there a special panel I can get that would have those switches?

Thanks!
Robert.