I have a Canon D60 - and while it has a cable, I never use it. I don't know what "Stitch Assist" does - but I use the panoramic software that stitches multiple images together into one - provided you take them with about a 50% overlap.
You also need to pivot the camera around the same point if possible. It takes practice. I usually shoot panoramics for stitching from left to right with a 50% overlap in each. I do that be looking at an object in the center, and then as I pan to the right, I place that at the left edge. Then repeat the process as many times as it takes. The same procedure can be used in verticals.
I currently use Jasc's Aftershot for processing software. It has built in to it the stitching software developed by Enroute (now defunct.) It is a simple procedure where you drag and drop frames into the matrix and then left the software create the composite based on your preserences for perspective or cylindrical view.
This is my 5th digicam - and I have been doing this for about 7 years now, and after the first camera, have never connected the cameras to any computer. I use media reader/writers inserted in a USB port.
There are other software packages that will stich pan shopts - do a Google search for Panoramic Stitching.