LWJGL has a OpenAL binding so any info on OpenAL will apply. The first place to look for information will be
www.openal.org. There you can find some documentation.
As for your question, OpenAL only allows mono or stereo by default. There seems to be an extension called LOKI_quadriphonic that allows 4 speaker output. But I'm not sure if it's supported or how it works.
Also, I'm guessing that 3d sounds can be rendered to all available speakers, but again, I'm not sure it does. Only got stereo here, so I can't test.
