Interesting thought process, Sendaz, but I really can't entirely see where it comes from. I won't argue about the possibility of a metahuman-spirit-driven homonculus/golem, as I don't have any serious knowledge of EarthDawn, but I find it unlikely to do so, when it's so much easier (not to mention legal) to bind an Ally to one.
In any case. Longshot, the corporations - or rather, every cybernetics/bioware scientist ever - has wondered how to cram as much 'ware into a body while keeping it alive. Like any facility anywhere, someone bitched about the 'hard limit' at one point or another to a friend or colleague who was doing research on conjured spirits, ritual magic, blood magic, symbolic links, and/or the controlling and binding of ghosts. In essence (pun intended), one thing led to another, and the two of 'em got permission from the money men to start experimenting.
Where the 'ancient knowledge' comes in might refer to several places - either the dragon (Great or otherwise, corrupt/toxic or otherwise) that's rumored to be an integral part of Aztechnology, or the vampires (possibly ancient) who are definitely at the core of the Ordo Maximus, or a blood shaman who managed to wrangle the secret of such bindings from her mentor/totem spirit. It's possible, but not likely, that one of the Immortal Elves or any of the known Great Dragons was involved; they seem to prefer a 'clean' manasphere as much as possible.
The critical knowledge is the magic to control a metahuman spirit, really. We can keep bodies on life support for years IRL; we have no control over the person's soul, and none such has been published in Shadowrun material - for good reason.