Well I have always done the rest by the HDS so I cant say for definitively but if you can do the ECU reset the old fashioned way then I suppose you could do it by this procedure
Turn the ignition switch ON (II), and wait for 2 seconds.
Start the engine, and hold it at 3,000 rpm with no load( no air con no radio nothing) until the radiator fan comes on.
Let the engine idle for about 5 minutes with the throttle fully closed
that will do it .
Well, I had been on a long trip after posting, and thought it had solved it. Unfortunately not. So I tried this procedure. I took it to 3000 in neutral, for 3 minutes or so. I couldn't tell if the fan had come on, maybe it didn't, but either way the revs came down to 800 then down to 650! I left the car in idle for 3 minutes or so. On re-ignition the revs started at 1100 then dipped immediately to 900, then slowly dropped to 650 in fluid succession. Job done. So if there was a thumbs up smilie, I'd be using that.
I did actually charge it up in situ before. And as Pepster states, the charging current of these is low, but if in doubt look at the charging instructions of your charger or FAQ on their website. For ctek they specifically state that their chargers work without need to remove batteries, Interestingly they say that they recommended negative to ground rather than battery because:
"All CTEK chargers observe the directives that apply in the EU. All battery chargers whatever the brand must be approved in line with the same standards. Many more basic chargers can cause the battery to emit a significant amount of oxy-hydrogen gas and also generate a spark when connecting. This represents a major risk of injury and it is therefore stipulated that the first terminal should be connected away from the battery in order to reduce the risk. A CTEK charger is spark free, has a minimal amount of gassing and can therefore be connected directly to the battery. However, we do not recommend this for approval reasons." -
Now whether thats marketing talk or whatever, who knows, but I thought that as much as batteries and charging them can be interesting, if at all, its something to be mindful of.
Thanks folks, its worth a discussion and hopefully will help other people if they have idle issues.
Steve