Bootcamp if he has an Intel Mac would be first choice, imo.
Parallels 5 works well on any modern dual core Mac, too. A bit heavy on system resources for a mid-range 2.4Ghz C2D 2GB RAM machine but it'll do it well if you make it emulate a 2.0GHz Celeron w/ 512MB of RAM and 128MB video.
Word is with Wine it'll crash when it starts raining, and you can't log into the zone until it stops. It rains a LOT in EQ
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If he/she is using a MacBook with the multitouch trackpad, scrolling will be a bitch. Ie zooming the camera in and out from your character, crap like that, but otherwise it will work fine. They'll need to use Function+FKey to use the Mac's function keys.
I've answered this same question at least a few times around here :P
Now, there IS a native Mac client, but iirc it was for a seperate, Mac-only server (which is retarded) and it will NOT work with EQEmu