I don't think anyone has built one successfully without major drawbacks.
Home brew kits seem to involve the taurus rack, see chpsk8t (you'll have to search extensively for it). The Taurus rack creates bumpsteer and wide turning radius.
There are commercial kits like, total control products, Randall's rack, speeddirect, and an outfit in Austrailia.
The tcp rack seems to get good reviews. Of course the price seems to be typical of upgrades for classic falcon bodies, 3000$.
I went with the Randall's rack, it has a slightly larger turning radius (about 3-5 feet). Still, my cougar still turns sharper than my 2003 sable (friggin' tank).
As far as building one yourself, it's a tall order. Such a feat will require considerable fabrication skills. I think Ronstang is working on something new, but it appears it will be a while before he goes public.
I have the TCP power rack, and what's impressed me most is that it isn't overly light like the old powersteering, so I have gotten a lot more road feel. And it's easy to install.