Do you mean using poses on Antonia that were made for V4, or the other way around? I'll assume the former.

I don't actually know if there is something like a pose converter that supports Antonia. If there wasn't one and I still wanted to use poses from another figure (say V4) on Antonia, I'd probably start by loading some of them into Antonia 1.0 and see if they seem useable with a reasonable amount of tweaking. This is because, as you may or may not remember, the root of the body part hierarchy was original called hip, but got renamed to waist in Antonia 1.2.

If this looks good, it should be easy to do a simple search-and-replace on the pose files to make them work with the Antonia 1.2/WM/SE gang. If the figure in question also has a waist actor (I honestly don't know which ones do) there's probably a better way to do the conversion, but this should get you started.

-- I'm not mad at you, just Westphalian.