I am sure you can do it, but once you get into using the D2 electronic autobox then you need the CAN bus set up for the two ecu's (engine and autobox) to chat to each other about the weather and when they might change gear, and probably once you switch the CAN bus on, the ecu's start looking for other ecu's like the BECM, SLABS, instrument pack etc so they can chat to those as well, and then if none of those other ecu's are there it probably all panics and starts emitting bongs. Other possible problems are that the gearbox ECU probably wants to know what the vehicle road speed is, which on a D2 comes from the ABS sensors via the SLABS ECU, and you won't have any of that fitted (well not unless you REALLY want a project...) and probably other stuff I haven't thought of.
But this is all assumption so hopefully somebody who knows for sure will be along
However I think the fact that Ashcrofts who do it for a living have settled on an alternative solution probably suggests it is a monstrous PITA to make it work. I wonder if Dave is around to comment on this?