Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Global Matrix
GV_MG_SAMPLEEFFECTOR_IMATRIXParameter: Color
GV_MG_SAMPLEEFFECTOR_ICOLORParameter: UV
GV_MG_SAMPLEEFFECTOR_IUVParameter: Weight
GV_MG_SAMPLEEFFECTOR_IWEIGHTParameter: Time
GV_MG_SAMPLEEFFECTOR_ITIMEParameter: Global Matrix
GV_MG_SAMPLEEFFECTOR_OMATRIXParameter: Color
GV_MG_SAMPLEEFFECTOR_OCOLORParameter: UV
GV_MG_SAMPLEEFFECTOR_OUVParameter: Visibility
GV_MG_SAMPLEEFFECTOR_OVISIBLEParameter: Weight
GV_MG_SAMPLEEFFECTOR_OWEIGHTParameter: Time
GV_MG_SAMPLEEFFECTOR_OTIMEParameter: Strength
GV_MG_SAMPLEEFFECTOR_OSTRENGTH