Sorry this repo has not been maintained in a very long time and i will pull it down soon.
Packages for the vbox modules for these kernels were never provided, but the dkms packages for the modules should work (virtualbox-host-dkms, virtualbox-guest-dkms). Make sure the headers package (pacman -S linux310-pae-ck1bfq-headers) for the kernel is installed before installing the vbox dkms packages and rebooting.