XGBoost in Python: How do I input the scale_pos_weight for multi-classes?

Question

I have 3 classes and my weights are
Class 1: 1
Class 2: 0.333
Class 3: 0.167

How do I input them into the scale_pos_weight parameter?

I know for a binary classification, we input it like below:

model = XGBClassifier(scale_pos_weight=99)