I believe Jodi at weldingtipsandtricks.com has a video on that that shows it very well. It's basically exactly what it sounds like, where when you hit the trigger on the torch it slows ramps up the amperage over however long the machine is set for (assuming this one is adjustable, I can't remember for sure whether it is or isn't). That way you get the benefit of being able to ramp amperage up and the beginning and down at the end without using a foot pedal.
Here's a page on it, but can't find the video
http://www.weldingtipsandtricks.com/...ngs-part3.html