how can we grant iReceivables payment option to Internal Employees

Hi gurus,

            We are in the process of implementing iReceivables . I am able to grant access to this module to external customers without issues.

            Now we have to open this module to Employees so that they can pay off  their Invoices( in ebs we don't have invoices for them now, but eventually will have).

            These people are EMPLOYEES and we already have them in Oracle HR/Payroll module and they do have a FND_USER created as we are using iProcurement module.

            Trying to link an existing customer to an FND_USER gives error "Emplyoee and Customer must be same person".