I had a similar problem and found I could do something along these lines with VB by importing the dataset into a recordset and then looping through each pushpin in the recordset and setting its ballon state.
Code:
Dim gappmp As New MapPoint.Application
Dim objMap As MapPoint.Map
Dim objRecords As MapPoint.Recordset
Set gappmp = CreateObject("MapPoint.Application")
gappmp.NewMap "C:\AnyFolder\AnyMap.ptm"
gappmp.Visible = True
gappmp.UserControl = True
Set objMap = gappmp.ActiveMap
Set objRecords = objMap.DataSets.Item(1)
Do While Not objRecords.EOF
objRecords.Pushpin.BalloonState = geoDisplayBalloon
'BallonState can also be geoDisplayName or geoDisplayNone
objRecords.MoveNext
Loop
objRecords.MoveFirst
Hope this helps.