You should not need to follow any instructions from PayPal, as those are designed for using their cart and purchase buttons.
When you use E-junkie cart and purchase buttons, we receive PayPal IPN and do all validation and processing required for that. See our help page on selling phone card PIN codes here:
http://www.e-junkie.com/ej/help.selling-codes.htm
If you need to activate the PINs before selling, that would be entirely up to you and unrelated to our system. If your card/PIN issuer can receive PayPal IPN-style transmissions to activate PINs automatically, see our third-party integration instructions here:
http://www.e-junkie.com/ej/help.integration.htm