No. Kepler cards GTX 640 (*), 650, 660, 670 and 680 (and their Ti variants) do not need GraphicsEnabler=y or any other type of injection or modification done to driver files.
They have been natively supported since 10.8.3 and under normal circumstances work fine out of the box. I believe this goes for the 700 series as well but I haven't looked into it.
Your own 610 is a rebranded GT 520 which is Fermi architecture, not Kepler. (*) There is also a Fermi architecture version of the 640, based on the GT 545.
I know you're trying to help, but be careful when you do. oldnapalm's guide is good but it is outdated by now.
Giving someone the wrong information can cause confusion and more problems than it was meant to solve.
(but you get points for suggesting to boot in verbose mode and posting a screenshot).
Unless he's using an older version of OS X, his issue is probably Chameleon not being able to detect the correct PCI Root, or maybe he needs the npci=0x2000 kernel flag. If he has upgraded from some other video card, maybe there is stuff left over from that, now causing a conflict.
balls: Post more information. As your post is, all it does is raise more questions.
Always include your full specs, system version and install method when asking for help.