Do you mean Tarent or UlmPunk? Both can be downloaded from
www.illwinter.com. The mod format changed only little between the games, so depending on how the mod was done it could work with Dom3 with little or no changes. Balance would be widely different, of course, as gold was much less plentiful in DomII. Also, units' resource costs weren't automatically calculated, so units had much higher #rcosts (resource costs). Any new weapons added by a mod should be given resource costs, and all hamanoid units' resource costs should be brought down to 1.
Tarent works, replacing Sauromatia instead of MA Ulm. That would be changed simply by changing #selectnation 4 with #selectnation 31.
Ulmpunk would need a bit more work, because it uses #newmonster in addition to replacing MA Ulm's own units. The id numbers that were assigned to these units are chosen via DomII standards, and are now occupied by Dom3 units. All #newmonster commands would have to be changed, in addition to changing resource costs and #selectnation.