you did not answer all of my questions
requireSSL on the forms element will make the server not accept any cookie unless using a secure ssl connection, it will also flag new cookies as secure so the browser does not pass it unless using a secure ssl connection. The cookie must be issued after changing this to true, it will not change the flag on an existing cookie that has already been issued, so the browser may still pass that cookie but the server would not accept it. To get a new cookie you would have to logout and login again after changing requireSSL to true.
This is a feature of ASP.NET forms authentication it is not specific to mojoPortal. See also the article Use SSL.