...... I've answered my own question :)

The following code should do it.... [Untested yet].

1. Add the SharpZipLib from the \bin library to the reference section of your local project [If not already there....]
2. Add the folowing imports [C#: using].... at the head of the file

3. Add the following code:

 Public Function CreateZipFile(ByVal strFile As String, ByVal targetName As String) As Boolean
CreateZipFile = false
Try
    Dim strmZipOutputStream As ZipOutputStream
    strmZipOutputStream = New ZipOutputStream(File.Create(targetName))
    ' Compression Level: 0-9, 0: no(Compression), 9: maximum compression
    strmZipOutputStream.SetLevel(9)
    Dim strmFile As FileStream = File.OpenRead(strFile)
    Dim abyBuffer(strmFile.Length - 1) As Byte
    strmFile.Read(abyBuffer, 0, abyBuffer.Length)

    Dim objZipEntry As ZipEntry = New ZipEntry(strFile)
    objZipEntry.DateTime = DateTime.Now
    objZipEntry.Size = strmFile.Length
    strmFile.Close()
    strmZipOutputStream.PutNextEntry(objZipEntry)
    strmZipOutputStream.Write(abyBuffer, 0, abyBuffer.Length)
    strmZipOutputStream.Finish()
    strmZipOutputStream.Close()
   CreateZipFile = True

    Catch ex As Exception 
        DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(Me, ex)
    End Try

End Function

My thanks to JohnR of SharpDevelop who provided the baseline for this snippet. the SharpLib documentation and C#/VB samples can be found at http://www.icsharpcode.net/OpenSource/SharpZipLib/Default.aspx

Imports System.IO
Imports ICSharpCode.SharpZipLib.Zip