Credit card type is detected automatically when the customer enters the credit card number.
After the payment method is activated in X-Cart:
http://kb.x-cart.com/display/XDD/Connecting+X-Cart+5+and+X-Payments#ConnectingX-Cart5andX-Payments-Configu...tionXCartAdmin
You can change its name from Elavon or PayPal to something like "Credit card (VISA, MC, etc)" through Store setup -> Payment methods -> Sorting & Descriptions