Cross-domain tracking code

Hi All, We have a domain [login to view URL] and we have a shopping cart at [login to view URL] , we would like to be able to track the visitors as the move from our main domain to our shopping cart. Currently we have implemented the JS attached ([login to view URL]) and it works perfect in transferring the cookie to the second domain. The issue is that it interferes with an existing code that we have in the website ([login to view URL]) . Basically, both put an onclick= code in the link and creates the issue. We are looking a proposed solution, either in the existing code or a completely new implementation. Our goal is all the links leading to our shopping cart to be rewritten automatically to click me Thank you