Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Volume Type
ID_VOLUMEBUILDER_VOLUMETYPE
Parameter: Voxel Size
ID_VOLUMEBUILDER_GRID_SIZE
Parameter: Interior Voxel Range
ID_VOLUMEBUILDER_HALF_BAND_MESH_INTERIOR
Parameter: Exterior Voxel Range
ID_VOLUMEBUILDER_HALF_BAND_MESH_EXTERIOR
Parameter: Spline Voxel Range
ID_VOLUMEBUILDER_HALF_BAND_SPLINE
Parameter: Particle Voxel Range
ID_VOLUMEBUILDER_HALF_BAND_PARTICLE
Parameter: Override Grid Matrix
ID_VOLUMEBUILDER_GRID_MATRIX_OVERRIDE
Parameter: Match Voxel Size
ID_VOLUMEBUILDER_MATCH_GRID_BUTTON
Parameter: Auto Update Settings
ID_VOLUMEBUILDER_AUTOUPDATE
Parameter: Update
ID_VOLUMEBUILDER_UPDATEBUTTON