Selectively load data using Oracle 11g r2 External Table Preprocessor

I am using the Preprocessor feature in Oracle 11g r2 to load several data files in a table. However, the raw files seem to have certain rows that shouldn't be imported with the rest. For example: col1 col2 col3 col4 A 1 2 3 A 2 3 4 B ab bc cd So, I want to only load the rows with col1 = 'A' and load the rows with col1 = 'B' into another table. How can I do this inside the processor?