Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Strength
SHATTEROBJECT_STRENGTH
Parameter: Angle Speed
SHATTEROBJECT_ANGLESPEED
Parameter: End Size
SHATTEROBJECT_SCALE
Parameter: Randomness
SHATTEROBJECT_RANDOM