Go to data/world/maps/campaign/triumvirate (the name of the campaign) and copy that folder to BI/data/world/maps/campaign/ That won't work though, because neither the factions nor the units in triumvirate exist in BI, so the game will crash. Fixing this is quite a long procedure, you'll have to include everything in BI or swap triumvirate units/factions with BI stuff. Look aroud for editing of descr_strat.txt and start working :D