My league has a World Baseball Classic every 2 years during the offseason.
Basically, I create a copy of the league file. Release all the players then delete all the teams, history, etc. Create a new league with the 8 WBC teams (2 divisions of 4). Move all the players onto the teams with logos, facegen uniforms, etc. I then manually schedule "Regular Season" games.
We have group stages which are 6 games for each team. The top 2 teams from each group meet in a semifinal and the winners of those play in a 3 game series for the final.
Teams
Group A
USA
Mexico
Canada
Japan
Group B
Dominican Republic
Cuba
Puerto Rico
South America
Here are the reports from our first competition: World Baseball Classic Home
It's a little bit of work to set up the league file, but it was a lot of fun having teams of our owners manage the WBC teams.