It's not how Plus! interfaces to messenger that's the thing- more how Plus! extends the messenger API. For example, what actually gets sent when trying to execute a change of font colour or /me.
You might want to take a look at Pai's Xniff to find out what gets sent and how. Note that you'll probably need a windows (virtual) machine to use it.
Man is least himself when he is in his own person. Give him a mask and he will tell you the truth. (Oscar Wilde)
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