creating default directory tree

[womd]

hello there!

wish: if a user is created via webinterface(mysql+php+"SQLHomDirOnDemand = on") , some subdirectories with individual "rights" shoult be created .... lets say .. there should be a directory named "upload"  and "public" in every user-home which is created..

any ideas in how to do this with proftpd ? is it possible to call a shell/php-script on a certain ftp command ? 


tanks for help