Need to develop a custom program to import AP Credit Cards as well as the Transactions done by Credi

Business wants a custom program to import AP Credit Cards as well as the Transactions done by Credit card in to iExpense.Actually Business will be using various credit cards and that needs to be imported in the system through custom interface program.

I have seen we have certain types of Credit card standard programs but that is not serving our purpose.As those are specific to one Credit card.Please provide the details and suggestion to implement custom solution.Please provide the APIs and Interface table and steps to perform.