Add the following <intent-filter>
to the Activity you want launched from the gesture:
<intent-filter>
<action android:name="android.intent.action.ASSIST" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
You will now see an option for your app when you make the swipe now, and will have to select it as the default handler by selecting Always, as shown below.