To create a Lumion 360 image, set up your scene in Lumion. Once it is ready, place your camera at the desired location and click the 360 sphere button, it is labelled as "MyLumion.com".
360 Sphere "MyLumion.com" button
You will be transported to a different menu where you can set different Viewpoints. Use the viewport window to navigate and click the "Set Viewport" button to create a 360 camera. The view will not look like a 360 image, but it will render as such.
Set Viewport button
When you have set all your views, click the "Render VR Panorama" button, adjust the settings to Stereoscopic and GearVR, and click "Start Rendering".
Start Rendering button
Once you've selected a directory and name for you file, click save and wait for the render to finish. You can use the resulting image in your InsiteVR project.