Download your kernel source you want and try to apply the patch.
If it tells you that it works, try.
If it tells you that there are rejected files (files that patch didn't manage to modify) then you have to do it yourself.
Anyway on this routing field, there shouldn't be a lot of differences between vanilla and distro-kernel. If there are, they should be documented.
The "patch" command does not work.
You should tell us the exact message. And take care about the directory names. (just edit the patch, you will see that the maintainer has put his kernel tree in v2.6.19/linux )