Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Knife
MDATA_BRUSHMODIFIERBASE_ENABLEDParameter: Strength
MDATA_BRUSHMODIFIERBASE_STRENGTHParameter: Invert
BM_KNIFE_INVERTParameter: Pinch
BM_KNIFE_PINCHParameter: Push
BM_KNIFE_PUSH