If you don't find a source for the serial cable, there are a couple of options:
(1) build one using the wiring diagrams contained somewhere in this list's
archives, but this requires a hard-to-find 9-pin mini-DIN connector
(2) replace the 9-pin mini-DIN socket on your Ultralite with a PS/2-style
mini-DIN serial connector (has anyone actually done this?), but this
requires some handiness with assembly/disassembly and soldering
-- -Brian Smithson brian@grot.starconn.com