The ListBox modus provides an option to initialize a box with a given set of particles. This modus uses all functionality from the List modus itself. The only difference is that one has to specify the length of the box.
Modi: ListBox: File_Directory: "particle_lists_in" File_Prefix: "event" Shift_Id: 0 Length: 10.0
Apart from that the usage should be equivalent to the List modus. So for more details please check the List userpage.