In most cases, it is possible to upgrade an older Disklavier with modern features, including internal memory, USB for MIDI, USB flash drive support, internal tone generator, CD drive, remote access with an iPhone, iPod touch or iPad, and even DisklavierRadio™ and DisklavierTV™ in most cases.
The upgrade is a new control unit called the DKC-850. In most cases, it replaces an existing control unit. In other cases, it functions as a piggyback control unit that connects to the old unit with MIDI cables.
The DKC-850 package comes with all the cables that you need and detailed instructions, including pictures for how to connect everything. Anyone can install the upgrade. A technician is not required.