As of now, I have this working for the following Object Layers (the SettingsObjectLayerType enum in .NET API):
Code:
AlignmentLabeling
AlignmentTable
AppurtenanceLabeling
CatchmentLabeling
FittingLabeling
GeneralNoteLabel
GeneralSegmentLabel
GradingLabeling
GridSurfaceLabeling
IntersectionLabeling
MatchLine
MatchLineLabeling
MaterialTable
ParcelLabeling
ParcelSegmentLabeling
ParcelTable
PipeAndStructureTable
PipeLabeling
PointTable
PressurePartTable
PressurePipeLabeling
ProfileLabeling
ProfileViewLabeling
SampleLineLabeling
SectionLabeling
SectionViewLabeling
SectionViewQuantityTakeoffTable
StructureLabeling
SurfaceLegendTable
SurveyFigureLabeling
SurveyFigureSegmentLable
TinSurfaceLabeling
ViewFrameLabeling
Important to note that this is applying CLAYER to the resultant Objects, and does not in any way change the Style's use of Layers for Style Components; those will still show up normal per your Style's settings, this just places the Label Object on CLAYER for annotation layer management & plan production purposes.
Cheers