Custom Properties
Look into DatabaseSummaryInfo structure and DatabaseSummaryInfoBuilder class.
Usually you use DatabaseSummaryInfoBuilder class to manipulate information from Database.SummaryInfo property (DatabaseSummaryInfo structure), and after you done with the information, you update the information back to Database.SummaryInfo.
In this case, the equivalent you are after is:
Dim custProp As Object = DatabaseSummaryInfoBuilder.CustomPropertyTable(key)
