Thanks Pollofrito. Got mine to work that way. Worked like a charm.
I think if I were to add to this guide would be:
Open Atom's package manager
Search for atom-ternjs and install it
A button that says "View Code" will become available under the package name. Click it.
The package directory will open as a "project".
Navigate to node_modules > tern > plugin, and right-click "show in explorer/finder"
paste the phaser.js file you got from the tern-phaser folder (or you can find the code here https://github.com/angelozerr/tern-phaser/blob/master/phaser.js )
Open a phaser project, to to Packages > Atom Ternjs, and "save and restart server". This will open the config code for your project
Paste this (update ecmaVersion as appropriate for current phaser compatibility)
{ "ecmaVersion": 5, "libs": ["browser"], "plugins": { "phaser": {} } }
9. If needed, restart Atom.