The KM500 riveting tool turned up and I had a few goes on some old chain bits and links. to use it on the XT I took of the top chain guide so I could sit on a crate and do it. fitted the new link and O rings , used the tool to press on the side plate. then riveted the pins. It took a few goes and I kept taking the tool off and measuring the pin flare ( see the guide for dimensions) http://www.didchain.com/chainTools.html
I also found a few clips on U tube, this was the best
https://www.youtube.com/watch?v=EkY3Kd8Zgz0

Eventually got there, but I think Ive pushed the side plate on too far as 2 of the O rings now bulge out the side a bit but I was happy with the way the rivet heads turned out. The link still moved freely so wasn't to bad. Took the bike for a run to stretch the new chain a bit and all was OK, no cracks in rivets and the O rings didn't look any worse.
I have now ordered another 2 rivet links and will definitely do it again to sort the O ring problem. The tool is also a cutter but will only press out pins with the heads ground off.

So overall all I found its not rocket science but you do have to buy the right tool for DID chains and be a bit careful , especially if you,re of to france shortly.
I,ll let you know if it breaks!

Dave