Wix Embedded Sqlite

CustomAction.cs

public class CustomActions
{
    [CustomAction]
    public static ActionResult BuildIndex(Session session)
    {
        session.Log("Begin building index");

        try
        {
            EmbeddedAssembly.Load(string.Format("BuildIndexAction.{0}.SQLite.Interop.dll", Environment.Is64BitProcess ? "x64" : "x86"), "SQLite.Interop.dll");
        }
        catch (Exception e)
        {
            session.Message(InstallMessage.Error, RecordException(e));
            return ActionResult.Failure;
        }

        // Do the custom action

        return ActionResult.Success;
    }
}

EmbeddedAssembly.cs

/// <summary>
/// Load Assembly, DLL from Embedded Resources into memory.
/// </summary>
/// <param name="embeddedResource">Embedded Resource string. Example: WindowsFormsApplication1.SomeTools.dll</param>
/// <param name="fileName">File Name. Example: SomeTools.dll</param>
public static void Load(string embeddedResource, string fileName)
{
    byte[] embeddedResourceBytes = null;
    Assembly curAsm = Assembly.GetExecutingAssembly();

    using (Stream stm = curAsm.GetManifestResourceStream(embeddedResource))
    {
        // Either the file is not existed or it is not mark as embedded resource
        if (stm == null)
            throw new Exception(embeddedResource + " is not found in Embedded Resources.");
                
        // Get byte[] from the file from embedded resource
        embeddedResourceBytes = new byte[(int)stm.Length];
        stm.Read(embeddedResourceBytes, 0, (int)stm.Length);
    }

    string tempFile = SaveOnDisk(embeddedResourceBytes, fileName);

    // Load it into memory
    IntPtr result = LoadLibrary(tempFile);
    if (result == IntPtr.Zero)
    {
        Exception e = new Win32Exception();
        throw new DllNotFoundException("Unable to load library: " + fileName, e);
    }
}

[DllImport("kernel32", SetLastError = true, CharSet = CharSet.Unicode)]
private static extern IntPtr LoadLibrary(string lpFileName);

// Saves the specified byte array in the temp folder with the specified filename
private static string SaveOnDisk(byte[] data, string fileName)