@radek @charming I have written a notebook on how to use architectures like senet which have been taken from https://github.com/Cadene/pretrained-models.pytorch and incorporate into the fastai library.
Special thanks to @radek for giving me a hint on using ConvLearner.from_model_data.
Link to the notebook : https://github.com/TheShadow29/FAI-notes/blob/master/notebooks/Using-Pretrained-Pytorch-Models.ipynb
I have also posted this here: Using Pretrained Models from Cadene repository