I figured this out, here is class i now use to generate and register a type
library from a .net assembly:

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using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;

namespace ValidatorApp
{
    [ComVisible(false)]
    public class TypeLibrary
    {

        [DllImport("oleaut32.dll")]
        private static extern int LoadTypeLib([MarshalAs(UnmanagedType.LPWStr)]
string libPath, ref IntPtr ITypLib);

        [DllImport("oleaut32.dll")]
        private static extern int RegisterTypeLib(IntPtr ITypLib,
[MarshalAs(UnmanagedType.LPWStr)] string libPath,
[MarshalAs(UnmanagedType.LPWStr)] string helpDir);

        [DllImport("oleaut32.dll")]
        private static extern int UnRegisterTypeLib(ref Guid libID, Int16
wVerMajor, Int16 wVerMinor, int LCID, SYSKIND syskind);

        [ComImport,
            GuidAttribute( "00020406-0000-0000-C000-000000000046" ),
            InterfaceTypeAttribute( ComInterfaceType.InterfaceIsIUnknown ),
            ComVisible( false )]
            public interface UCOMICreateITypeLib
        {
            void CreateTypeInfo();
            void SetName();
            void SetVersion();
            void SetGuid();
            void SetDocString();
            void SetHelpFileName();
            void SetHelpContext();
            void SetLcid();
            void SetLibFlags();
            void SaveAllChanges();
        }

        public static void RegisterTypeLibrary(string AssemblyPath, string tlbPath)
        {
            //Convert assembly to type library file
            TypeLibConverter TLC = new TypeLibConverter();
            Assembly asm = Assembly.LoadFile(AssemblyPath);
            ConversionEventHandler eventHandler = new ConversionEventHandler();
            UCOMICreateITypeLib typeLib =
(UCOMICreateITypeLib)TLC.ConvertAssemblyToTypeLib(asm, tlbPath, 0,
eventHandler);
            typeLib.SaveAllChanges();

            //Now register the type library
            IntPtr obj = IntPtr.Zero;
            LoadTypeLib(tlbPath, ref obj);
            RegisterTypeLib(obj, tlbPath, "");
        }

        public static void UnRegisterTypeLibrary(string tlbPath)
        {
            //1. Call LoadTypeLib function to get ITypeLib interface pointer
            //2. Call GetLibAttr method of ITypeLib interface to get pointer to Type
Library attributes
            //3. Call UnRegisterTypeLib to unregister type library

            IntPtr obj = IntPtr.Zero;
            LoadTypeLib(tlbPath, ref obj);
            System.Runtime.InteropServices.TYPELIBATTR TA = new TYPELIBATTR();
           
            System.Runtime.InteropServices.UCOMITypeLib myLib =
(System.Runtime.InteropServices.UCOMITypeLib)Marshal.GetTypedObjectForIUnknown(obj, typeof(System.Runtime.InteropServices.UCOMITypeLib));
            myLib.GetLibAttr(out obj);
            TA = (TYPELIBATTR)Marshal.PtrToStructure(obj, typeof(TYPELIBATTR));
       
            UnRegisterTypeLib(ref TA.guid, TA.wMajorVerNum, TA.wMinorVerNum, TA.lcid,
SYSKIND.SYS_WIN32);

        }

    }

    [ComVisible(false)]
    public class ConversionEventHandler : ITypeLibExporterNotifySink
    {
        public void ReportEvent( ExporterEventKind eventKind, int eventCode,
string eventMsg )
        {
            // Handle the warning event here.
        }
   
        public Object ResolveRef( Assembly asm )
        {
            // Resolve the reference here and return a correct type library.
            return null;
        }    
    }
}