hsphereplugins

We are utilizing WHMCS exclusively to sell software. Our Software is Server Software which will always be downloaded to a linux Server. Our old Software had besides the normal download link a link that the customer could use with wget on the Server WITHOUT needing to login again. This was accomplished by displaying a link with a random parameter like: on http://www.website.com/whmcs/index.php?download=d73dka84kf5jjj5678786422 this link was active for a short period of time. Would it be hard to implement this or, could I write this myself via Hooks? I looked which places I could hook into but was unable to find a hook related to downloads.