Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Random Seed
OP_BORN_SEEDParameter: Birth Type
OP_BORN_BTYPEParameter: Count
OP_BORN_COUNTParameter: Rate
OP_BORN_RATEParameter: Shot
OP_BORN_SHOTParameter: Life
OP_BORN_LIFEParameter: Life Variation
OP_BORN_LIFEVARParameter: On
OP_BORN_IN_ONParameter: Animation Time
OP_BORN_IN_ATIMEParameter: Birth Count
OP_BORN_OUT_PARTICLECOUNTParameter: Birth Num
OP_BORN_OUT_PARTICLENUM