Спасибо, добрался сам. Код, если кому интересно:
Sub NewDataFrame()
Dim i As Long
Dim mxd As IMxDocument
Set mxd = ThisDocument
Dim pMap As IMap
Set pMap = mxd.Maps.Create
pMap.Name = "New"
pMap.IsFramed = True
mxd.Maps.Add pMap
Dim pMFr As IElement, pMF As IMapFrame
Set pMFr = New MapFrame
Dim pEnv As IEnvelope
Set pEnv = New Envelope
pEnv.PutCoords 10, 10, 20, 20
pMFr.Geometry = pEnv
Set pMF = pMFr
Set pMF.Map = pMap
Dim pGC As IGraphicsContainer
Set pGC = mxd.PageLayout
pGC.AddElement pMFr, 0
mxd.UpdateContents
MsgBox mxd.Maps.Count
End Sub