beignet : OpenCL implementation for Intel GPUs ( https://01.org/beignet )
libgdev : Gdev is open-source GPGPU runtime ( https://github.com/shinpei0208/gdev )
ocl-icd : Alternative to vendor specific OpenCL ICD loaders ( http://forge.imag.fr/projects/ocl-icd/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a gentoo-gpu
For Paludis use this rsync : rsync://gentoo.zugaina.org/gentoo-gpu-portage
If you have a problem : ycarus(-at-)zugaina.org