Create a Controller for your integration call it say Integration Controller
Class IntegrationController extends CController {
public actionPage1(){
$this->render('page1');
}
}
For each page create an action and move your pages into the corresponding views/integration folder as page1.php, page2.php and so on.
You can access page1 with <app_root>index.php?r=Integration/page1 and page2 with <app_root>index.php?r=Integration/page2 so on and so forth.
If you want different routing create more controllers and actions accordingly.
Ideally you should move you Business Logic away from view files such as page1.php into the controller and models. But this will get you quickly integrated even though it is not best MVC practice.
In addition to this you will have to reroute all your ajax requests within the code accordingly.
For example your old request when to a page called "myoldpage.php",
$.get({
url:"myoldpage.php"
....
you can use Yii createUrl class and create the new url in the url attribute like this
$.get({
url: <?php echo Yii::app()->createUrl('Integration/newPage'); ?>
Note: This controller structure works in Yii1.x, Yii2 will be slightly different