It's not easy, but it's possible:
How to Share Session State Between Classic ASP and ASP.NET
Loading User Information from Channel 9
Something went wrong getting user information from Channel 9
Loading User Information from MSDN
Something went wrong getting user information from MSDN
Loading Visual Studio Achievements
Something went wrong getting the Visual Studio Achievements
It's not easy, but it's possible:
How to Share Session State Between Classic ASP and ASP.NET