I have no idea how to eliminate an O2 sensor...there were M42 cars that ran a CO pot in the AFM instead of the O2 sensor in Europe. There's a disconnected wire pair on the firewall you can connect to configure the DME for European no O2/no cat.
Is there some sort of an AFR constant in TunerPro for closed-loop? If the DME wants to run 14.7:1 all the time, you won't be able to tune it properly.
Post some pics, a project thread, or attach the maps if possible. I've considered doing this myself but I've never gotten around to it. I'd love to get rid of the stock ICV and the AFM. If that's possible from TunerPro instead of a complete standalone like VEMS it'd be superb.