Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Draw
BELT_DRAW
Parameter: Set
BELT_SET
Parameter: Clear
BELT_CLEAR
Parameter: Show
BELT_SHOW
Parameter: Belt on:
BELT_LINK
Parameter: Influence
BELT_F
Parameter: Influence Map
BELT_F_MAP
Parameter: Hover
BELT_S
Parameter: Hover Map
BELT_S_MAP