VBA Code:
Dim pMxDoc As IMxDocument
Set pMxDoc = ThisDocument
Dim pGC As IGraphicsContainer
Set pGC = pMxDoc.PageLayout
Dim pElement As IElement
Set pElement = pGC.FindFrame(pMxDoc.FocusMap)
Dim pEnvelope As IEnvelope
Set pEnvelope = New Envelope
pEnvelope.PutCoords 1, 1, 6, 6
pElement.Geometry = pEnvelope
pMxDoc.ActiveView.Refresh