I want to run a Blade Runner game and I've got Call of Cthulhu, and that's as far as I want to go - I could get BRP but the sheer amount of options would do my head in. I want it fast, easy to use and in my comfort zone, and Call of Cthulhu suits me just fine.
The first thing I'd lose is the magic points, of course, and I'd replace the 'Sanity' score with a 'Humanity' score. You'd work it out the same way and roll against it when seeing something horrific, such as a murder or a nasty act of violence, and this is way of becoming desentisised to it. Humanity lowers with acts of violence and choices of an immoral nature, but rises with acts of heroism, kindness and things considered selfless.
Replicants would start with a very low Humanity score - say, one-fifth of a standard starting score - which makes them easier to spot, especially with a Voight-Kampff machine. But, if a player plays one then there's always a chance that they could become a lot more human as they experience and do things like a normal human being. This would make them cling to life much more when the fourth year came along.
Other than that, I'd treat it like Sanity for both human beings and replicants, along with all the neurosis and phobias that come with it.