How to add new animations for Biped model

In 2025.2 we can now animate entities with custom models, but I also want to add custom animations to entities using the Biped model, without having to recreate the Biped model and all its animations from scratch trying to match how they look like, how could I use the Biped model and then add custom animations to it? How do I see the names of the block groups in that model?