stsadm cannot do what you are asking unfortunately, however you can achieve the same functionality using SharePoint Designer, which will create a .cmp (which is a cab file by another name) file which you can import using either stsadm or SharePoint Designer as you prefer.

Here are some links to SharePoint Designer as well:

 - [SharePoint Designer 2007][1] (works with WSS3 and SharePoint 2007)
 - [SharePoint Designer 2010][2] (works with SharePoint 2010, 2007 and
   WSS3(last 2 with reduced functionality))
 - [SharePoint Designer 2013][3] (works with SharePoint 2013)

  [1]: http://www.microsoft.com/en-gb/download/details.aspx?id=21581
  [2]: http://www.microsoft.com/en-gb/download/details.aspx?id=16573
  [3]: http://www.microsoft.com/en-GB/download/details.aspx?id=35491