Computer controlled force-field

I'm trying to use a computer to turn on my tekkit classic force-field. I want to be able to input activate to turn it on and have it stay on. and later input a diffrent passcode to deactivate it. Any tips or suggestions would be very welcomed and apreciated. Also i need it to automaticly run on startup if possable. Many thanks in advance, I hope to one day concour this Lua beast.

Im assuming you can use redstone to controll it, so just use the redstone API for that.
to read user input you can use read()

redstone.setOutput("back",false)
while true do
  local input = read()
  if input == "activate" then
    redstone.setOutput("back",true)
  elseif input == "deactivate" then
    redstone.setOutput("back",false)
  end
end

To run it on startup, just name the program "startup".