Shopping Cart Integration

Hello,

I want to integrate the Membership Plugin with a Third Party Shopping cart, WSO Pro, that uses Pay Pal Express.

They state that it can be done using
http://warriorplus.com/support/knowledgebase.php?article=11

The details are on the link I just provided but basically I need to use IPN Forwarding and/or a Key Generation URL.

So my question is, is this possible and how hard would it be to do?

I am not a programmer but would like to know what to expect should I hire one.

Thanks,

Matt