Credit Card Payment Page

My credit card processor has a simple XML interface. I already have a module for my shopping cart. What I would like is a simple application which has a back-end where I can enter a single transaction information (customer, amount, etc.) and then email a link to the customer (referencing the transaction ID generated by this application) where they can put in their credit card information. This would be submitted to the credit card processor and, once approved, that transaction ID would be marked completed and the link not reusable. There is no need for integration with any shopping cart or accounting system.