You shouldn't do it, I know. I mean, perPer the XML specification you aren't supposed to. Stop reading this answer. It's a hack!
Having said that... I really needed it badly, so here's the trick. Surround the section you want to comment with an unused processing instruction:
<some-tags /> <?comment <!-- traditional comment 1 --> <badtag prop1="123"> <!-- traditional comment 2 --> </badtag> <!-- traditional comment 3 --> ?> <rest-of-my-tags /> You can use any processing instruction that's not in use. I chose "comment" as the unused processing instruction, so I started the big comment with <?comment and ended it with ?>.
Pretty much any word will do as a processing instruction, since they aren't really used most of the time. I mean, when was the last time you used one?