The new syslinux package (4.03-4) now includes a default configuration file at /boot/syslinux/syslinux.cfg. If you get a file conflict during update, run:
mv /boot/syslinux/syslinux.cfg /boot/syslinux/syslinux.cfg.sav pacman -S syslinux mv /boot/syslinux/syslinux.cfg.sav /boot/syslinux/syslinux.cfg