Add Custom Field for Customer in SimpleCart Script

Hello, I need something added to my website where my customers can include their bitcoin wallet address and it can be included within the SimpleCart paypal checkout so that I can send them their bitcoin after receiving and approving the PayPal payment. It would be cool if the custom field where they paste their bitcoin address was near the bottom end of the shopping cart on the website. That way, after the buyer is all done shopping, they would then paste or type their bitcoin address and hit Checkout which could be directly below the custom field, and then be taken to the PayPal Checkout just like how it is on the website right now except have the custom field and it's customer contents included as a custom PayPal field so it is included in the PayPal transaction as custom notes, and then I (the seller) can see it and send the customer their bitcoins during or after I approve successful payment. My website is [login to view URL] and is hosted on Google Blogger. I am using a template that is using the e-commerce shopping cart called SimpleCart, which I believe is in Javascript. You can edit the website code by going to the main dashboard of the blog, and then going to Template, and then within Template > Edit HTML. Please get back to me ASAP, I will also be on Skype and would prefer that we communicate that way. Thanks so much! Skype: coinwwweb