nVidia has released 304.108, which among other fixes, is approved for kernel 3.10. I am so far successfully using it with 3.10.7 an amd64 box (with just a few ~amd64 packages). However, I have not been able to determine if it is officially ok with any 3.10.x or only specific versions. Reproducible: Always I simply modified the 304.88 ebuild by changing the kernel restriction check from ge 3.10 to gt 3.10. I do not know if any other changes are needed or appropriate.
It's in the tree. Thanks for the report.
It took me a while to figure out what to do. I was about ready to add a comment to that other, very lengthy bug about nvidia drivers and kernel versions, when I found some other version bump bugs. I've been using Gentoo for a while now, so I'm not sure whether I forgot or if it's just not posted prominently enough. Anyway - thanks for the quick response.