I have just posted links to the Threefold Wrathful One Initiation of Vajrapani, Hayagriva and Garuda by Lochen Rinpoche. The empowerment is in 7 parts on Youtube.
This joins other information on practices such as the Fire Sword of Black Garuda.
The site link is: http://bluegaruda.com/garuda-buddhist-sadhanas/
The videos explain what the practice requirements are and what elements of an empowerment, such as vows, may be necessary. In general, in-front generation of the deity is the norm, with those already holding an HYT empowerment being able to self-generate as, for example, Black Garuda.