Changing the default screensaver folder

Hi…
I´m using my Apple TV to upload an display pictures from my Nikon wireless transmitter. There is no problem uploading via FTP to the box, but what i need is to be able to show my photos in either the screen saver or using the slide show. Only problem is, that i can´t find that option .

I can see my pictures in the FTP server , but i can´t find my pictures using the apple tv interface…

Any of you guys tried this ?

Jacob