It is news to me that there exists a latex package manager for Arch Linux, so now you do not need to manually install anything latex related. You can enter the package manager and it works in a similar way to apt-get on Ubuntu/Debian/.
Get the following pacakge from AUR, texlive-localmanager-git or you can use yaourt/packer to install it. Stay away from the non git version it exits with an error as of now.
After you have done installing run, tllocalmgr. Then type,
install <package name>
Run texhash as super user to refresh the hashes. The packages should be available to you now, thanks to fellow archers!