In case you're not aware of exactly what we're talking about, the CM Installer is an easy — some say bulletproof — way to swap the software on your supported phone out and install CyanogenMod. You need a computer for this sort of thing, and the Android application was a helper to make sure you have everything set up and ready, both on the phone (or tablet) itself and the computer you're using. Before, this was a Microsoft Windows-only affair. Now it's not.
Getting started is easy enough, you'll just join the Google+ community and follow directions in the sticky post to download and install. Not sure you're ready to start doing things like flashing phone software? That's good — it means you're thinking. Jump into the forums for your Android device and poke around a little to see what's involved and how people are doing all this.