Apache mongrel and IIS..hosting asp and rails on same server

I am running ASP.NET on IIS and on the same server am running rails. I
have started multiple instances of mongrel as service and apache does
the load balancing.
THE PROBLEM IS i want to run the ASP.NET website on IIS and at the same
time run the rails website through apache mongrel combination(Suggest
any better way if you have). Since I can only run one website at port
80. How am I to achieve this.? Also I want my primary server to be IIS,
i.e if any routing is done it should be done from IIS to apache.
Please help.
Thank you.