This may have been covered before, but actually it is possible to crossfade ac3 in womble. Just not automatically. (as in you can't just hit a fade button).
You just load 2 tracks that overlap in Womble, use the point audio editor, have one fade out and the other fade in overlapping. Sorry this isn't a very detailed explanation, but I'm sure anyone who is willing to do this is capable of figuring it out.