Well that did it - I now have working cruise control
So if anyone else is having a similar problem here's a summary of the key points that aren't described in detail in the "cruise control" rob the Viking document (Part 2).
Code the CAS and FRM modules using "FA_WRITE" in NCS Expert. When you get to the part where you have to "Now we need to tell the DSC system and the rest of the modules that we have installed the retrofit", the descriptions get rather more vague. Here's what I had to do.
Restart NCS expert as before, load profile, f1, f3, choose chassis/module (cas), back. That should have written the full car trace file fsw_psw.trc to the ncsexpert/work folder. I renamed my fsw_psw.trc file to .man (because the man file was empty - that was the problem all along).
Following the instructions again - the job was already SG_CODEIREN, the guide says push "F4 process car" and wait. For a start its F3, not F4, I wasn't sure which was right but it is F3 "process car", then F1 "code car" - this isn't mentioned in the guide at all. Then you have to wait while the coding runs which takes a little while. Lights and gongs go off, and eventually I got an error in CABD, (as I have seen others get), but this seems to be ok (so far). Other's have said to code the DSC unit rather than the whole car, but I'm not sure how to select it individually. The whole NCS Expert is very user unfriendly (and I'm no expert!). I have no idea what really is going on, it was just trial and (mainly) error.
The guide then says to run DIS to reset the steering angle sensor , this took me ages because DIS runs on a VM and I couldn't set the VMware network properties so I had to reinstall XP. Plus DIS takes a long time to actually get to the bit to reset it (and its very vague in the guide on what to do). Dont do that - as other people have said, just use Tools32, load the module (DSC_89 in my case), and then double click the 'lenkwinkel_dsc_abgleichen' (quite a way down in the first list box). the lights WILL GO OFF AND STAY OFF!.
I now can see the cruise speed in the window. I didn't make any changes to anything else.