Add Customer Reference field to Payment Gateway

Setup: We are using wordpress as the CMS, with the plugin Events Manager, and a custom coded Gateway Plugin Extension that feeds into the Swedish payment processor SveaWebPay. (All links are at the bottom of the description. ) We use SveaWebPay for both online credit card payments, and invoicing (two different gateways. ) Now we want to add a special field called Customer Reference, and add that to the call to Svea Web Pay. I’ll try to explain the background: If the customer is ordering on behalf of a company (or municipality) we need to give the option to fill out a Customer Reference field, so that the municipality finance office knows how to process the invoice. The Customer Reference should of course be passed on and printed on the Invoice. I checked with Svea Web Pay and the best place to put that is as a CustomerReference field, but because of limitations on the SveaWebPay end, this only works if the customer is a company, and not for private individuals. So: What we need to do is this If the user selects “Kommun/Företag” (Company) when using the Invoicing option, a second text-field should appear. This should then be added to the order as a CustomerReference field and passed on to Svea. (The text field should not show up if the user selects Individual instead of Company. ) Here are links to some useful resources: Example of a payment form on site: [login to view URL] (choose Faktura instead of Kontokort at the bottom to see the current form in action. ) Documentation: Event Manager Plugin: [login to view URL] SveaWebPay: [login to view URL] (The CustomerReference class information can be found on page 12 ) I am attaching the current payment gateway that needs to be extended. I am also attaching a screenshot of where the new field should show up. I am looking for anyone who knows what they are doing, so the total time to finish this project is likely to be less then the time it took me to write up this summary. If you are not that person, then this project is not for you. If you have not read the brief before you post a statement: "I can do this, just need more information" without explaining exactly what more you need, then I will most likely ignore you or even mute you. Other then that, all are welcome! Turnaround should be less then a day.