Finally figured it out.
Here are the steps in a bottleneck to help a fellow in need.
1) Edit /etc/sudoers with visudo and add this line.
<your-user> ALL=(ALL) <commands-you-want(with path) or ALL(for all commands)>
2) Type sudo to check if it is installed. If not, then install it.(http://linuxg.net/how-to-install-and...-slackware-14/
3) Once installed, open /etc/profile, look for PATH and add ':/sbin' at the end before double quotes or other path if the command is in another folder and save.
5) Login back with the user and try 'sudo <your-command>. It should work now.