[Tiwaz]

As far as I know, this is very difficult, if not impossible to do. Although it is true that all of the games you mentioned utilize the Quake III engine, it doesn't necessarily mean that they are alike.

Consider MoHAA and Spearhead, for instance. From what I heard, Spearhead maps are not 'compatible' with MoHAA, because the maps in Spearhead use an altered/modified Q3 engine. So just extracting a map from a Spearhead .pk3 wouldn't work.

I guess that if it were easy, we would have seen some MoHAA servers running Spearhead maps by now. Since a lot of I-have-been-playing-MoHAA-since-day-one-I'm-not-a-nooby-EAGames-ruined-MoHAA-with-that-damn-expansion-patch-that-was-way-to-expensive people aren't really fond of Spearhead. Including myself.