Are you sure about that? The Jewel Ornament doesn't discuss things like ngondro.
Just a little history question here guys....
Was the ngondro put together by the 9th karmapa? I can't remember -
What's the history of the ngondro?
The liturgy was composed by 9th Karmapa, Wangchuk Dorje, and has been updated by the lineage masters since then--in regard to the supplications to successive Gurus of the Karma Kagyu Mahamudra lineage.
Prior to this text, however, the practices of refuge, Vajrasattva, Mandala and Guru Yoga were part of the "full sadhana" of various yidams--6th Karmapa, Thongwa Donden, wrote the main sadhana of Vajrayogini, for example, and you'll find similar liturgy (though not exactly the same) there....
Basically, I think the Four Extraordinary Preliminaries have traditionally been a part of the preliminaries on the path of Skillful Means--Creation and Completion, Highest Yoga Tantra, Six Yogas of Naropa, etc., but the stress on "Ngondro" practice as a self-sufficient complete practice, culminating in Guru Yoga, as the basis for the path of Liberation--Sahaja Mahamudra--was developed over time in the Karma Kagyu lineage, and formalized by Wangchuk Dorje, who also wrote the most common training manuals in that tradition, the Ocean of Certainty, and the shorter ones....and I should note that Wangchuk Dorje's text does include a short "Daily Recitation" for yidam practice, so we can say it stresses the Path of Liberation, but doesn't avoid any of it's "roots" in the Path of Means.