In 2016, the Tsadra Foundation sponsored a series of talks on the Treasury of Precious Instructions focusing on Kongtrul and the specifics of the Eight Chariots.  Translator and teacher Sarah Harding who has been immersed in this work for decades and has completed several volumes of this work leads it.  Also included are Elizabeth Callahan and Acharya Tenpa Gyaltsen.  You can listen or download the full series here.