The config should be located in /boot. You can copy it to /lib/modules/3.10.101-7/osmc/.config.
You also need the kernel headers. Quickest way to get them is:
sudo apt-get update
set -- $(cat /proc/cmdline) && for x in "$@"; do case "$x" in osmcdev=*) sudo apt-get update && sudo apt-get install -y "${x#osmcdev=}-headers-$(uname -r)"; ;; esac; done
Then you will likely need to symlink the build/ directory to the headers. For some reason, this is not working reliably in kernel builds. If you have problems, I will take a look in to this in more detail.
Sam