Hellcat said : "This can only be done via pretty unsecure uploading scripts or such...."
And if your host is not profissional, you will face some problems with him.
A friend of mine, had givem me my config.php, and I was confused about this, I don't have any upload script on my site but ecdownloads only, and it's secure.
I don't allow members to upload files at risk rates.
He could to create files in my active 777 directories.
So I moved to a new host. and protected my active 777 directories.
Thanks