Well, the idea would be e.g. to click on "new tag" and add a few tags like you would add css styles. "name", "address", "occupation" etc. Then I would load my text file, select some words and click on the appropriate text. That would be much quicker than going through the code and copy past opening/closing tags or typing each tag with the risk of typos.
I could do some programming but convert e.g. a tab delimited file. But the problem is that each line would have more or less fields. E.g. one company has besided the address also 1 or more employees.
But anyway, there isn't any drag 'n drop xml editor anywhere? Indesign does it so I could do that (you select text and select the 'label' from the label pallette), but I'm surprised no xml editor does it.