This is an old problem for Xtgem users my elegantly simple solution uses a tiny javascript/Xtfunction snippet in the folder and a simple javascript call on the page

In the folder to be listed create a plain text file called filelist.js in this file write this code
document.write('<xt id="filelist" sort="2" />');
The value of "sort" can be changed
0 = last mod (old-new)
1 = last mod (new-old)
2 = name (a-z)
3 = name (z-a)
On the page where you wish the list to appear place this code
Don't forget to set the address to the address of the folder to be listed
<script type ="text/javascript" src="http://YOUR SITE/FOLDER/filelist.js"></script>
This is a demo listing from a folder on my site and one on another site