Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Pull
ID_CA_MUSCLE_DEFORMER_PULL_STRENGTHParameter: Slide
ID_CA_MUSCLE_DEFORMER_SLIDE_STRENGTHParameter: Fat Offset
ID_CA_MUSCLE_DEFORMER_FAT_OFFSETParameter: Initialize
ID_CA_MUSCLE_DEFORMER_INITParameter: Clear
ID_CA_MUSCLE_DEFORMER_FREEParameter: Distance
ID_CA_MUSCLE_DEFORMER_DISTANCEParameter: Pull Mode
ID_CA_MUSCLE_DEFORMER_PULL_MODEParameter: Pull Fall-Off
ID_CA_MUSCLE_DEFORMER_PULL_CURVEParameter: Stretch
ID_CA_MUSCLE_DEFORMER_STRETCHParameter: Strength
ID_CA_MUSCLE_DEFORMER_STRETCH_STRENGTHParameter: Iterations
ID_CA_MUSCLE_DEFORMER_STRETCH_ITERATIONSParameter: Stiffness
ID_CA_MUSCLE_DEFORMER_STRETCH_STIFFNESSParameter: Objects
ID_CA_MUSCLE_DEFORMER_OBJECT_LIST