heads up! 
We've already completed and releasing a new add on called
The Firetank Featured Product Manager that lets you do exactly this and more, if you're interested in the silent release (available for a limited time before the public release) please contact me on
http://www.firetanksoftware.com contact page.
It'll do dynamic products and HTML on static pages and a hell of alot more.
And it does it all WITHOUT screwing with your x-cart files. No modifications needed. ZERO messing around with php and admin files. It's in one of our clean break out interface in marketing manager style.
We've been using it internally for our own clients for over a years, it's been refined down over time and we're now releasing it.
It does not affect your tables or admin area.
Versions for x-cart 3, x-cart 4.0.X and x-cart 4.1.X are available.