I think it's great that people are working on PIN solutions for Joomla! shopping carts, as I believe there is demand for it.
That said, I want to warn everyone planning to sell PIN codes with a website. I managed to get a PIN solution working for VirtueMart and quickly abandoned it. The main problem has to do with chargebacks. If a dispute is filed, online payment processors like to see lots of interaction between the shop and the customer via emails. If you do not have this interaction with the customer you will likely lose the dispute, even if the PIN has been redeemed by the customer.
I am not talking about people buying codes, redeeming them, and then opening a claim on the grounds that the PIN code was not valid or already used. I'm talking about claims of unauthorized use of the credit card or PayPal account. If all you have to show is an order# and a system email sent out, you will likely suffer the chargeback along with some cancellation fees.
I think the solution to this is to add some interaction with the customer into the PIN system. For example, an email can be sent thanking the customer for the order, with a link that "activates" the code in the DB. Once the link is clicked, the PIN is ready for transfer to the customer. The client should be required to either log in and download the PIN code, or log in and click another link that tells HikaShop to email the code, either in the body of the email or as an attachment.
These extra coding steps were way too deep for me, and my humble shop could not warrant the investment necessary to hire this work out. I wish everyone good luck in your endeavours.