urgh had to create an account... cheers for the link, looks like what i needed to know:
Turns out the button on the end of my estate's wiper stalk is a lot different to this one, the bit that pushes through to close the contact is offset and the second part's locating lugs are right at the end of the 3cm tube, so you'd never get to them with anything. So even if I had levered the button out first (which I decided against as I thought it would do too much cosmetic damage) I still wouldn't have been able to get to the contacts without ripping the lugs off.
So if I read that right, I'm going to end up snapping the clips which hold the rear wiper section onto the main section?
Arse.
Think I'll do it with the door shut and some paper on the floor so I can find and superglue the clips when they snap. I'll use feeler gauges (got separate metric+imperial) to release the button, and then apart from the gluing fun I guess it'll just be a case of either (with luck) bending the button contact back into the enclosure so it's not permanently contacting, or (without luck, but likely) finding a way to stick it back onto the enclosure if it's come away. Can't tell from the pictures if it's clipped in or if plastic comes through holes in the copper then is melted to hold in place. Guess I'll find out soon enough...
Really don't want to go down the new com2000 route - apart from the expense, there's just too many variants which are insufficiently described on ebay. I can see cruise, stereo and rear wiper on ebay pictures, but auto wipers can be hard to make out, and I have no idea how to tell if they've got ESP and auto lighting
I do have to get the airbag off soon though, MOT less than a month away and there's an airbag fault likes to come up. Thought it was the pretensioner (pretty sure pp2000 reported it as such) but I jabbed at the horn with the engine off yesterday and triggered an airbag fault suggesting it's the wheel one. Which is good - the pretensioner on these appears to be in the reel itself, not under the seat

so will involve lots of faffing to get to
<steve_earwig> I think this forum is more about keeping our cars going with minimal outlay than giving our cars more reason to go bang