Hello,
I use O!Direct to stream mp3 to my Asus O!Play HDP-R1. To generate a playlist I simply copy the files into one directory. Then I sort the files by my program FileSortRenamer and stream it to the box. The program can be found here: http://www.andreas-pernau.de.vu/Software.htm
Naturally you can use it for sort and rename other type of files like jpg or avi. It's simple to select many files and move them up, down, to top or to buttom.
Perhaps this programm will be helpful to one or the other.
Best regards