Hi Damian !
I was sure you'll be the first to answer,
As i will forward this info to my server admin, can you explain a little more (i have understand what you mean without getting how to do realy do it) :
"write a small PHP script to handle the files in the way that you want. Another solution is to install a php file manager."
Better, do you know such a script ?
I just would like to remind that the goal is to set properly Tikiwiki as sinlpe as possible then that i'll be able to modify files on my own... not to get things more complicated !