This would certainly be possible.
Please take a look at this forum post which demonstrates how a gallery's XML file can be generated dynamically when the gallery is displayed.
Rather than immediately output the XML data (via PHP 'echo'), you could modify the code to save the XML data to a file (ideally named 'config.xml' so that you do not have to change anything in a default gallery setup). Knowledge of PHP would be required.
You could then set up a Cron Job (scheduled task) on your web server to run the PHP script (to update the XML file) once a day. (Your web hosting account's cPanel might have a Cron Job interface which would make this very easy to achieve.)
I hope this points you in the right direction.