Maybe not an exact answer to you question but hope it helps...
Code:
objDataSet.Symbol = 1
You can set the symbol for a dataset (see above) but I dont think it changes pushpins already on the map. The following code could be used to change the symbol for pushpins already on the map.
Code:
Dim objDataSet As MapPointCtl.DataSet
Dim objmap As MapPointCtl.Map
Dim objRecordset As MapPointCtl.Recordset
symbolNumber = 1
Set objmap = MappointControl1.ActiveMap
For Each objDataSet In objmap.DataSets
If objDataSet.Name = "My Pushpins" Then
Set objRecordset = objDataSet.QueryAllRecords
Do Until objRecordset.EOF
objRecordset.Pushpin.Symbol = symbolNumber
objRecordset.MoveNext
Loop
End If
Next