Handling multichannel source audio

Someone at Beyondunreal.com recently discovered that some of the tracker files composed for Unreal and Unreal Tournament are multichannel:

Multichannel Music Tracks - BeyondUnreal Forums

To create a rip of these, I've been using XMPlayer (ModPlug makes subsong handling kind of clunky, and Winamp seems to pre-amp everything with Diskwriter). XMPlayer makes a very clean, direct WAV rip a tracker playthrough, but it's stereo PCM.

I'm kind of clueless on how to preserve the multichannel audio; I've never dealt with it before. As part of my Unreal collection, I have rips of the tracker songs / subsongs (since the subsongs and some loop patterns are not easily accessible without XMPlayer), and so to make a totally accurate rip, I'd need to somehow get this multichannel effect preserved. I've read that FLAC supports it, but I still have no experience with this kind of thing.

Edit: Just to make it a little more clear, I'm wondering if 1) multichannel information can be saved in a WAV file, and 2) if anyone might know more about ripping it. The Beyondunreal guy used MPT, so I'll probably play with it a bit.

Jam it back in, in the dark.

Yes, WAV has definitely multichannel support, see here e.g.:
Microsoft DirectX 9.0 SDK

I'm afraid I can't help you with the rest though. Maybe the app already extracts properly but your player simply can only read the stereo part.

There's nowhere I can't reach.