How to pass an array of structures from MFC to C#

I have a legacy MFC application that I wish to have interact with a C# library.

In C# I have something like:

namespace MyManagedLibrary
{
	[ComVisible(true)]
	[StructLayout(LayoutKind.Sequential, Pack = 4)]
	public struct MyStruct
	{
		public int data1;
		public bool someFlag;
		public double syringeSize;
	}

	[ComVisible(true)]
	public class MyClass
	{
		public void Set(MyStruct structures, string path)
		{
		}
	}
}

I build MyManagedLibrary and create a type library that can be imported in to the legacy unmanaged application, the MyClass.Set(...) function becomes something like:

	void Set(SAFEARRAY * structures, LPCTSTR path)
	{
		static BYTE parms[] = VTS_UNKNOWN VTS_BSTR ;
		InvokeHelper(0x60020004, DISPATCH_METHOD, VT_EMPTY, NULL, parms, structures, path);
	}

From the tlh file I can get a definition of MyStruct but when if I try from managed code: