[IronPython] defined in multiple assemblies (framework 3.5)

[Fernando Correia]

I'm getting lots of trouble trying to upgrade a C# project that
embedds IronPython from Beta 1 to Beta 4. We target the 3.5 framework.

The project has some assemblies and a website. I was able to make the
assemblies compile by adding a reference to Microsoft.Scripting.Core
and setting the alias to MSCore. In the source code where I use
IronPython I inserted this line: extern alias MSCore.

But in the website that uses these assemblies, I am getting 244 errors
like this: The predefined type
'System.Runtime.CompilerServices.ExtensionAttribute' is defined in
multiple assemblies in the global alias; using definition from
'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET
Files\website\4ab7ec98\acce05f3\assembly\dl3\b6dd741b\00e0903e_70f2c801\microsoft.scripting.core.DLL'

and also: 'ExtensionAttribute' is ambiguous in the namespace
'System.Runtime.CompilerServices'. InternalXmlHelper.vb.

I can't see a way to assign an alias to a reference in the website,
since Microsoft.Scripting.Core.dll is just copied to the Bin
directory.

I think I have the latest version of the framework. Even installed the
Visual Studio 2008 Service Pack today, along with .NET Framework 3.5
SP1.

It seems I am stuck with Beta 1... can someone give me some help?