If I’m not mistaken, the only special thing about the BWF format is that it contains extra data such as timecode and therefore won’t do what vsv wants.
To vsv, if it’s a 5.1 surround track you want to import, you’d need to save them out as separate channels in another application that offers this feature.
If it’s six separate channels, they can be imported separately and then lined up in Vegas.
My apologies if this is not what you’re after but saying “six channel in wav container” still doesn’t tell us much.
Mike