Import/Export Tool Need Another Column Added For Import

I am on version 1.5.3.1 and am using the Import/Export tool found at the following url:

http://www.opencart.com/index.php?route ... _license=0

I am needing to have another column on the import file. The name of the field in the database is "linkto" and it in the category table. Does anyone know what I would need to change in the coding to be able to import this specific field?

Thanks,

-Brandon