I think you should use the N9 (Reference Information) Segment.
The first element (N901) is the Qualifier, where you need to agree with the receiver of the document, what qualifier should be used for credit card information. In this example, E4 is used for "Credit Card Number", so you would have the following:
http://www.hibcc.org/EBUS/EDI%20Public%20Comment/H850v21.pdf
N9*E4*[Your credit card number]~ (Where E4 is N901 and the credit card number is the element N902)
Morten la Cour