I don`t really think describing the Level D 767 CDU/FMC helps with the problem on the iFly747.  Incidentally, if you check the manual on the 767 you`ll find its 400 for the LNAV, 1000 for the VNAV and 1500 for the AP.  The problem with the 747 is not so much how to use it but to get the unit to pick up a pre programmed flight plan in the co route part.   It says to use a 767PIC, this does it as a .RTE flightplan. The examples are FLTPLAN types, easy enough to do in fresh flightplans but the FMC fails to pick up any of them.  In fact, even the two supplied plans don`t work with the FMC.

Reider