Bootstrap : I think that's not proper way. The best way in my opinion is an ember-bootstrap addon.
ember-bootstrap uses the Bootstrap CSS classes while replacing the behaviors from the components Bootstrap implements in bootstrap.js, such as toggle, navbar, modal, etc., with equivalent, CSS class-compatible native Ember components.
Foundation: There is an addon called Ember CLI Foundation 6 SASS, it's also installed using command line.
| Parameter | Usage | 
|---|---|
| Ember install | Download a new extension package using Ember | 
| npm install | Download a new extension package using node.js | 
| SASS | CSS language necessary in Foundation | 
| Ember-cli-build.js | File with Ember imports, configuration, etc. | 
| {{#bs-modal-simple}} | Creation of a new bootstrap modal | 
| fade=fade | Set the modal animations | 
| {{#bs-button}} | Button with a Bootstrap cool look | 
| {{#bs-form onSubmit(action = "Submit")}} | New form with an action after submitting | 
Both addons are not mine, I thought it will be nice to present them to You, there are github pages of addons: 
Ember Bootstrap:
https://github.com/kaliber5/ember-bootstrap 
Ember foundation 6 https://github.com/acoustep/ember-cli-foundation-6-sass
You can find documentation there.