Concerning the can't get proc entry error, it disappeared after I removed the USB cable (I don't know if this is related, though).
Concerning the PDF document, I knew it, but it doesn't help, since the Fn combinations are different on the SL-C860. In particular, I wanted to map Fn+u to some symbol. I thought the keycode were 2013 (as Fn+o is 2015 and Fn+a is 2017), but it doesn't work.