Hi Jeff,
Not very sure but you can consider checking the component GS_CMSRCH , which provides you searching an attachment document through keywords , date , user etc.
Follow these steps :
The search is run through the class : CL_CRM_CM_GENIL_COMP
method : get_dynamic_query_result( ) by passing all the required parameters.
Convert the PHIO of all documents retrieved above , to their respective LOIO . ( FM : SKWF_PHIO_LOIO_GET )
Then you can find out all the BPs in which this document is used by running a select query from the table : SKWG_BREL. ( Refer FM : CRM_KW_DOCUMENT_ROOTS_GET and SKWF_IO_TO_RELATIONS_GET ).
/Hasan