HA!!!!
This was rubberducking 101.
It occurred to me while writing that I hadn't actually seen any log files, so I fired up "eac3to -test" with logging, and just before reporting ArcSoft DTS Decoder as not being installed, WINE reported errors concerning mscms.dll.
It appears to be a library that has to do with graphics, so I'm not sure why it's being referenced here (perhaps because the DTS decoder is just a subset of a much larger library that deals with video decoding)...
Anyway, I copied it from my Windows XP machine, and set it in winecfg to be preferred over the built-in version, and voilá!!! IT NOW WORKS!!! YAAAAAAAYYYY
Overall, MeGUI works pretty awesome in WINE
