1 website project, 2 forms authentication logon pages?

Hi all,
I have created a "web site" solution in vs2008. I am using forms authentication for this site. The site actually has 2 mini sites in it that share a lot of code, which is why I chose a web site solution instead of a web project solution. However, since it has 2 mini sites in it, I want to have 2 seperate logon forms. How can I set up thw web site solution/web.config/whatever so that it has 2 different logon forms, and it redirects you to one or the other depending on what page you were trying to get to?
 
Thanks 
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