I believe the Creative SDK DLLs will give you EAX hardware support. As for the setting call, I'm not sure what you'd have to set, but I'm almost sure that their libs will have the support.

See you're getting 3D sound either way, it's just enabling/disabling the hardware that will give you the EAX acceleration option in your games.

At least this is my best interpretation of how EAX & OpenAL works.

Of course you can always read more about it in one of Noeska's tutorials. Lesson 12 EAX Enviroment You can probably tell but he has done extensive work with OpenAL already.