PayPal authorization-capture needed on OScommerce Store

We have an OScommerce website that we are building [login to view URL] it is finished but we need PayPal authorization-capture installed into the payment system. This is different from the standard PayPal system. With authorization-capture the payment comes into your PayPay account, but it isn't completed until you press the 'capture' button and put in the amount you want to take. Has anyone seen this system before? This is the email I received from PayPal: To be able to use "authorization-capture" as you had previously, it's not an option within your Paypal account directly but you will need to do some modification within the code of the website (the name of the software you're using is OsCommerce I believe). What you need to do is to add the parameter "PAYMENTACTION" within the code your website is sending to Paypal during a transaction. By default, the value of that parameter is "sale" (which is a direct payment like the 6£ test from today) and you can change the value to "Authorization" to have the same process as before. Unfortunately, I wouldn't be able to tell you exactly where to add that parameter as I wouldn't be too familiar with the software used to create your shop but on page 35 of that guide, you'll find some details about the parameter and the value needed : [login to view URL]