Well, you can always wrap the text in a link. Typically the link color is different than the chat and echo colors... so I expect this would work for setting a specific string apart. It doesn't have to be a valid link that the game will be able to use, just one that looks usable until you click on it.
For example:
Charming \aNPC -1 whatever:A Lizard/\a
Charming A Lizard
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