I was hoping to get some help for an accessory that actually worked but I guess there are only one or two people out there who actually have a NuTone iPod setup (I guess it's too expensive for most who post).
In the end, this $300 "iPod? iCast Wireless Solution" from NuTone that was emailed to me looks like it might have to be the best we can collectively come up with on this newsgroup.
The only problem is that the literature doesn't say whether it works with the Nutone IM 4006 or not. So, I'm still looking about.