Ye its not that hard, a php file (include it every time your page is
loading or call it with a cronjob), that checks the modification date
of the .xcss files (via the xcss_settings array) and decides wether or
not to call the xcss class. the only problem is how to store the
modification dates of the time the files were created. I think the
best way is to safe it to a .txt file with serialize().