DotNetZip 中有一个使用 Stream 方法的示例AddEntry。  
String zipToCreate = "Content.zip";
String fileNameInArchive = "Content-From-Stream.bin";
using (System.IO.Stream streamToRead = MyStreamOpener())
{
  using (ZipFile zip = new ZipFile())
  {
    ZipEntry entry= zip.AddEntry(fileNameInArchive, streamToRead);
    zip.Save(zipToCreate);  // the stream is read implicitly here
  }
}
使用 LinqPad 进行的小测试表明可以使用 MemoryStream 构建 zip 文件
void Main()
{
    UnicodeEncoding uniEncoding = new UnicodeEncoding();
    byte[] firstString = uniEncoding.GetBytes("This is the current contents of your TextBox");
    using(MemoryStream memStream = new MemoryStream(100))
    {
        memStream.Write(firstString, 0 , firstString.Length);
        // Reposition the stream at the beginning (otherwise an empty file will be created in the zip archive
        memStream.Seek(0, SeekOrigin.Begin);
        using (ZipFile zip = new ZipFile())
        {
            ZipEntry entry= zip.AddEntry("TextBoxData.txt", memStream);
            zip.Save(@"D:\temp\memzip.zip");  
        }
     }
}