Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Random Seed
ST_SEEDParameter: Type
ST_TYPEParameter: Birth Type
ST_BTYPEParameter: Count
ST_COUNTParameter: Rate
ST_RATEParameter: Shot
ST_SHOTParameter: Life
ST_LIFEParameter: Life Variation
ST_LIFEVARParameter: Speed
ST_SPEEDParameter: Speed Variation
ST_SPEEDVARParameter: Size
ST_SIZEParameter: Size Variation
ST_SIZEVARParameter: X Fov
ST_XANGLEParameter: Y Fov
ST_YANGLEParameter: X Size
ST_XSIZEParameter: Y Size
ST_YSIZEParameter: Distance
ST_DISTParameter: Distance Variation
ST_DISTVARParameter: Spin
ST_SPINParameter: Spin Variation
ST_SPINVARParameter: Spin Type
ST_SPINTYPEParameter: Spin Axis
ST_SPINAXISParameter: On
IN_ST_ONParameter: Animation Time
IN_ST_ATIMEParameter: Emitter Alignment
IN_ST_ALIGNMENTParameter: Emitter Velocity
IN_ST_VELOCITYParameter: Emitter Position
IN_ST_POSITIONParameter: Birth Count
OUT_ST_PARTICLECOUNTParameter: Birth Num
OUT_ST_PARTICLENUM