UPDATE: I had a chance to do a few of these battery changes, using this method of 'on the bike' TPS sensor R&R last Sat. at a COG tech. day and wanted to let everyone know that it works well and pretty fast. Of course it gets quicker after doing a few of them :-) The last bike I did took just over an hour, and that includes both removing and re installing the sensors themselves on the bike, as well as opening both sensors, removing the old batteries and installing (soldering) in the new ones. So it is a pretty quick task and well worth doing IMO.
All sensors tested worked fine although I did not test any of the front wheels..... except the one where I mixed up the sensors on the bike and could not tell which one was front and which one was the rear. And before someone asks, yes, I did mark them but I ended up with both covers off both sensors at the same time and could not be sure which cover went with which sensor.... so the one marked 'R' might not really have been the rear. No problem though, a piece of string tied to the valve stem and spinning the sensor around turned it on (not that way!- easy boys!) so it displayed on the dash.
Brian