Once upon a time ... in a land far away ... oh ... sorry wrong story ...

A long time ago, I wrote a quick method to do a View All on the Product Listing ...

You could probably adapt this as it would show you where the changes are needed to make it go from the normal maximum display per page to a view all products status ....

See if this doesn't help ...

http://www.zen-cart.com/forum/showthread.php?t=38551

And yes, after you write it, this would be a very nice contribution to bundle up for others ...