I cant seem to find a getspecificfeature for form tool. This makes some sense as a form feature is made up of any number of features.
Also I tried to get at the featuredefinition.
Private Sub Button1_Click_1(sender As Object, e As RoutedEventArgs)
Dim swapp As New SldWorks.SldWorks
Dim modeldoc As ModelDoc2 = swapp.ActiveDoc
Dim selmgr As SelectionMgr = modeldoc.SelectionManager
Dim Feature As Feature = selmgr.GetSelectedObject6(1, 0)
Dim FeatureDefinition As Object = Feature.GetDefinition
featuredefinition was nothing. It looks like you would need to delete the feature, and re-insert it. InsertFormToolFeature Method (IFeatureManager)