Enabling apt-get on a default Amazon EC2 instance which has yum installed
Solution 1:
apt-get is a Debian tool. yum (and rpm) are Red Hat tools. They are not compatible; neither are the packages which they install.
If you want to use apt-get, use a Debian (or Ubuntu) image instead of Red Hat (or CentOS, or whatnot).
Solution 2:
YUM is the defacto RPM package management on RHEL (Centos) systems, and it works quite well once you get the hang of it- my very best suggestion is to familiarize yourself with YUM or use Debian...
That being said you can try to install one of these RepoForge packages (or set your /etc/yum/repos.d :D ) , then retry sudo yum install apt
http://pkgs.repoforge.org/apt/