Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Custom Number of Render Threads
PREF_RENDERER_THREADCUSTOM
Parameter: Adapt Thread Priority
PREF_RENDERER_THREADPRIORITY
Parameter: Lower Process Priority
PREF_RENDERER_LOWERPROCESSPRIORITY
Parameter: Create Renderer Log File
PREF_RENDERER_CREATELOG
Parameter: Show Global Illumination Info in Console
PREF_RENDERER_GLOBALILLUM
Parameter: Render Queue Log
PREF_RENDERER_RENDERQUEUELOG
Parameter: Auto Renaming
PREF_RENDERER_RENDERQUEUE_AUTORENAME