Bulk Load of EFT Setup Data?

We are going to be collecting numerous of customers EFT setup data to support pre-authorized debit payments. Upon discussing with a Lawson Engineer - it was suggested:

1) At Conversion Time: Use AR501 (Customer Conversion) - uses staging table ARCCUST
- this wil work nicely (and I've tested) - just include EFT setup data with the rest of the
customer data @ conversion.

2) Post Go-Live: was suggested to use AR550 (Customer Interface) - uses staging table ARICST
- I DO NOT want to alter any of the existing Customer data - but rather - just bulk-load the EFT
setup data for numerous existing Customers
- in attempting to test - getting the error message: "Cust Cannot enter EFT information on
Change action"
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Anyone have any experience here?

ALSO: I know which tables the EFT setup data is populating: FTCUSTNOTE & DTCUSTBANK
- anyone have any experience just hitting these tables via a "back-door"??