The closest I could find was in a PCI Security Audit Procedures and Reporting document, where Section 12.7 covers screening potential employees to minimize the risk of attacks from internal sources, which states:
"Inquire of Human Resources Department Management and determine that there is a process in place to perform background checks on potential employees who will have access to systems, networks, or cardholder data. These background checks should include pre-employment, criminal, credit history, and reference checks."
My advice would be to contact Visa and to ask them if they can supply more detail, or if their qualification process as an approved vendor will jump this hurdle along with others along the way to such status.
This was first published in October 2006