Sure you can add your own - in fact I thought you indicated with your first sentence that you had managed to do that already?
Adding and running .bat files is no problem at all. The only issue you may have is if you need a command window to stay open to see the results of some output. I'm sure there is a way of doing that with a batch files that uses start with some arguments but can't remember what they are off top of my head. I think you could also run python scripts directly if you didn't want a .bat file wrapper - specify python.exe as the executable and in the command line arguments column specify the path to the script.