The best way to do Facial Keypoints detection would be through Deep Learning. So, it would make sense to look for resources on machine learning instead of just facial recognition. A good starting point is to do the Neural Networks course on Coursera, which is being taught by Geoffrey Hinton.
Here are a few papers, you can refer to, but they are not in form of a tutorial:
Also, given that you would need to perform deep learning, it might make sense to try a few tools outside R. I have heard Lua Torch to be the most commonly used library for these computations. I read somewhere that Google, FB and the research group of Prof. Hinton all use Lua Torch for work on Deep learning - but I might be wrong!