C' est bon ca m' est revenu !
Pour Info, voila mon code, c' est pas academique mais ca marche !
Dim swApp As SldWorks.SldWorks
Dim Part As SldWorks.ModelDoc2
Dim retval As Boolean
Sub main()
Set swApp = Application.SldWorks
Set Part = swApp.ActiveDoc
Dim title As String
title = Part.GetTitle
Debug.Print title
Dim QuotQtéBelem As String
QuotQtéBelem = Chr(34) & "QtéBelem" & "@" & title & Chr(34)
retval = Part.DeleteCustomInfo2("", "QTEBELEM")
retval = Part.AddCustomInfo3("", "QTEBELEM", 30, QuotQtéBelem)
End Sub