Hi Old Fart,
In case the full-blown version of Photoshop (rather than Elements) is an option - its Photomerge function does what you're looking for brilliantly. I regularly create very large panoramas by merging as many as 56 originals into one seamless image - the program cuts, stitches, stretches, compresses and adjusts exposure, curves, etc. while you sit back and watch. I use a small 6 megapixel Lumix and I create finished images that can be printed 8 feet wide or more at 300dpi (or more!) From the finished print I can slice and dice into any number of panels with or without overlap.
To minimize the need for paneling I've been nurturing a relationship with a local high-end, large scale print shop, but I also have an Epson 3880 (17x22 and up to 17x37) on its way to me (I've been using a 13x19 R2400 for the past 6 years.)
The downside for using so many originals is the need for lots of computer power - my system has 24gb of ram and 1.5tb of swap disc for Photoshop's use and I sometimes forget that the Photomerge processing can take a lot of time on a slower system. Patience, though, yields results. If you're running into hardware issues, remember that RAM continues to get cheaper and cheaper...
Also, a tip - I learned the hard way to NOT let Photoshop use your SSD for its scratch discs! Generally there's lots less room available and the read/write is abysmally sloooow...
Good luck!
melvin