Apparently that's not true. .NET has a class called InstrumentedAttribute that exposes a property called SecurityDescriptor that seems to be what ChangeSecuritySettings is looking for.
ms-help://MS.VSCC/MS.MSDNVS/cpref/html/frlrfsystemmanagementinstrumentationinstrumentedattributeclasssecuritydescriptortopic.htm

(whine)