How to compile an assembly in Medium Trust

I have an unsigned custom assembly, that has been deployed to the bin folder of my website. Trying to access a page that explicitly serializes a list using LOSFormatter produces the following exception:

System.Security.SecurityException: Request for the permission of type 'System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. at System.Security.CodeAccessSecurityEngine.SpecialDemand(PermissionType whatPermission, StackCrawlMark& stackMark) at System.Security.CodeAccessPermission.DemandInternal(PermissionType permissionType) at System.Runtime.Serialization.Formatters.Binary.ObjectWriter.Serialize(Object graph, Header[] inHeaders, __BinaryWriter serWriter, Boolean fCheck) at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Serialize(Stream serializationStream, Object graph, Header[] headers, Boole ...