migrating: table basic information

Hi,
we used disknode for managing files in drupal5.
since that module is not supported, we decide to use a more conventional
approach, so filefield, filefield_source and imce are our choice.
Since is not possible to reference existing files, as they are not present
in the filefield table, I'd like to know the structure of filefield tables
and their names.
we have the "files" table with all files collected, and another table with
association between nid/fid used from disknode.
What kind of procedure I have to follow to acomplish the desired result?

Thanks in advance.