Hi,
You want to implement the needCC function in your payment plugin. It's really easy:
function needCC(&$method) {
$method->ask_cc = true;
return true;
}
Then, in the onBeforeOrderCreate function of your plugin, you can call the $this->ccLoad() function to load the credit card data entered by the user in your credit card form and you'll be able to access it like that:
$this->cc_number
$this->cc_month
$this->cc_year
...etc...
You can see examples of that in the code of the numerous payment plugins already displaying a credit card form like paypal pro, or authorize.net