Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Enable
VP_WATERMARK_TEXT_ENABLEParameter: Dynamic Layout
VP_WATERMARK_TEXT_DYNAMICLAYOUTParameter: Show Labels
VP_WATERMARK_TEXT_SHOWLABELSParameter: Time Code
VP_WATERMARK_TEXT_TIMECODEParameter: Render Time
VP_WATERMARK_TEXT_RENDERTIMEParameter: Active Camera
VP_WATERMARK_TEXT_ACTIVECAMERAParameter: Date
VP_WATERMARK_TEXT_DATEParameter: Project Name
VP_WATERMARK_TEXT_SCENENAMEParameter: Polygon Count
VP_WATERMARK_TEXT_POLYCOUNTParameter: Version Info
VP_WATERMARK_TEXT_C4DVERSIONParameter: Machine Info
VP_WATERMARK_TEXT_MACHINEINFOParameter: Take
VP_WATERMARK_TEXT_TAKEParameter: Footer
VP_WATERMARK_TEXT_CUSTOMParameter: Text
VP_WATERMARK_TEXT_CUSTOM_TEXTParameter: Background Opacity
VP_WATERMARK_TEXT_BG_OPACITYParameter: Vertical Alignment
VP_WATERMARK_TEXT_POS_YParameter: Font
VP_WATERMARK_TEXT_FONTParameter: Color
VP_WATERMARK_TEXT_COLORParameter: Background Color
VP_WATERMARK_TEXT_BG_COLORParameter: Enable
VP_WATERMARK_IMG_ENABLEParameter: Filename
VP_WATERMARK_IMG_FILENAMEParameter: Opacity
VP_WATERMARK_IMG_OPACITYParameter: Blend Mode
VP_WATERMARK_IMG_BLENDMODEParameter: Horizontal Alignment
VP_WATERMARK_IMG_POS_XParameter: Vertical Alignment
VP_WATERMARK_IMG_POS_YParameter: Margin
VP_WATERMARK_IMG_MARGINParameter: Scale
VP_WATERMARK_IMG_SCALEParameter: Keep Aspect Ratio
VP_WATERMARK_IMG_SCALE_ASPECTParameter: Keep Original Size
VP_WATERMARK_IMG_SCALE_KEEPSIZEParameter: Add Multipass Layer
VP_WATERMARK_ADVANCED_ADDMULTIPASSParameter: Render HUD
VP_WATERMARK_ADVANCED_RENDERHUD