I don't know about the ZIPPACKAGE. I'm using DotNetZip Library from CodePlex
]. It is easy to use in C# or VB.NET and the examples are good.
For instance the follow code would unzip all files in a WinZip file (using the DotNetZip code)
Private Sub UnzipFile(filename As String, targetFolder As String, password As String)
Using zip As ZipFile = ZipFile.Read(filename)
If String.IsNullOrEmpty(password) Then
zip.Password = password