Not completely sure what you are trying to do. If you have the selected elements, you can then just access the properties of each element and then check if the property is a textual property. Once you know it is textual, you know you have a label and can do what you want with it. Here is some sample code for rotating a label. In this case the name of the textual property can be passed into the function, but if not, it gets all the properties for the element. Once it gets the textual property, it rotates the label.
Private Sub SchematicRotateLabel(ByVal element As INgElement, ByVal blnUseGeographicRotation As Boolean, ByVal intRotation As Integer, ByVal strPropertyName As String)
Dim propMain As INgProperty
Dim prop1 As INgProperty
Dim props As INgProperties
Try
If Len(strPropertyName) = 0 Then
'just find all textual property
props = element.ElementType.Properties
Else
'get a specific property
prop1 = element.ElementType.GetProperty(strPropertyName)
props = New NgProperties
props.Add(prop1)
End If
For Each propMain In props
If propMain.Type = esriNgPropertyType.esriNgTextualPropertyType Then
If blnUseGeographicRotation = True Then
element.SetLabelEffect(propMain, esriNgLabelEffect.esriNgLabelTextAngle, GetArithmeticRotationValue(intRotation))
Else
element.SetLabelEffect(propMain, esriNgLabelEffect.esriNgLabelTextAngle, intRotation)
End If
End If
Next
element.Diagram.Redraw(esriNgRedrawMode.esriNgRedrawChange)
Catch ex As Exception
MsgBox("Unable to rotate text")
End Try
End Sub