I managed to figure it out by applying the same concept I used in inserting a group of columns. I don't know what this is called in the SQL documentation, it doesn't have a name, just a couple of parenthesis...

select * from table1 where (col1,col2) in (select col1,col2 from table2);

This creates a set of columns, and compares it to a list of set columns. The equivalent of:

select * from table1 where (col1,col2) in ( (2,1), (1,2), (2,3), (1,4) );

Does somebody know the formal name of this? Is it grouping?