The « Internet CustoPack.com » icon of RocketDock redirects to http://start.custopack.com. This website can change appearance functions of the pack that you have installed. However if you want the icon redirects to another page, you just have to change the URL following these instructions:
Note : CustoPack Tools doesn't change the default homepage of your web browser (except if you want to install the Ask bar). The Internet icon of Dock isn't an internet shortcut which will launch your web browser.