In my implementation of the Digitool, Darrel made up the box, and we used a
regular DB 25 cable  with one connector removed. I spliced (soldered) the DB
25 cable at the point where the wire harness goes into the connector which
enters the ECU. Net result, no modifications to the ECU. I have one chipped
(AMS, Digifant II) ECU and one stock spare that I swap around during trouble
shooting. No problem, straightforward if you read the Bentley wiring diagram.
Works perfectly.

Frank Grunthaner