sqlloader 8i dos part of filename as constant

hi,
I want to write a dos script that reads through a folder, picks up the files therein, and loads the contentvia sqlloader. But, each file is different, and I want to use characters 11 and 12 of each filename to identify the company code, and insert the value into the db table along with the data within the file for each row.
Effectively I want to use filename pos 11 and 12 as a parameter or constant, that gets loaded on every row as one of the columns (company code).
does nayone have any ideas? or better still an example script to do this?