I have a fairly unmodified version of OSC (2.2-MS2) installed, and I've just copy/pasted the six .php files to my catalog. I ran the database modification: ALTER TABLE `products` ADD `short_desc` TEXT; and it claimed success, so I've no idea why this is not working.
When I view product listings, I just see what used to be there. No extra text for product descriptions at all...
My Catalog
As far as I can tell, I've followed the instructions. I don't have much savvy with php or sql, but I'm no novice to html, and I have a copy of Winmerge that I used to insert the php changes, so I didn't have to type them in myself. I even tried flat copying over the existing files when the first try didn't work. I really want this mod but I'm clueless, clearly.