Protocol for serial mouse with wheel

Does anyone know the communication protocol used by an Intellipoint-style mouse which has a wheel?
There's lots of information out there about the Mouse Systems 5-byte
protocol and the Microsoft Mouse 3-byte protocol. But I haven't been able to find an updated spec for the new scroll wheel.
If nobody knows, I'll start disecting the protocol myself. (So if you are reading this in an archive and are looking for the answer, email me. One way or another I'll probably know by then.)
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