Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Strength
MELTOBJECT_STRENGTHParameter: Radius
MELTOBJECT_RADIUSParameter: Vertical Randomness
MELTOBJECT_VERTRANDOMParameter: Radial Randomness
MELTOBJECT_RADRANDOMParameter: Melted Size
MELTOBJECT_SIZEParameter: Noise Scale
MELTOBJECT_NOISESCALE