Wow, that was pretty impressive. Hooray for concatenation.

That was obviously just too easy, so here's another one. Now I'd like to be able to take the IPTC location tags (City, Sub-location, etc.) and add them to my shiny new XP Keywords. My first step was to try:

exiftool -City+>XPKeywords

but this didn't work because XP Keywords is not a list. Is there a way to append text to normal tags like this? I suppose I could first add them to IPTC Keywords and then copy the whole lot across, but that doesn't seem like the most efficient approach.