February 9th, 2011, 15:00
Posts: 1,404
Threads: 53
Joined: Apr 2006
It should be possible. I once opened a warlords scenario up in vanilla for adventure 16. You should be able to do it by loading the save up in vanilla, going into the worldbuilder, then saving the worldbuilder file in a location you remember. Then open BTS and go to Play a Scenario and select the worldbuilder file.
EDIT: You have to save the vanilla worldbuilder file in the BTS public maps folder, then change the extension to .CivBeyondSwordWBSave. Then open BTS and go single player, custom scenario and it should be the first one on the list. Select the leader you want to play as and then save the game on the first turn.