The viewport preview feature is already available in the default Blender projects which are created by the App Manager. See below for the information on how to enable if you didn't use the App Manager to create your asset files.
To enable the viewport preview in Blender, select "Material" in the "Viewport Shading" menu. Also select "GLSL" on the "Shading" panel and enable "World Background" on the "Display" panel - both these panels can be found in the "Properties" window (which is, in turn, revealed with the "N" shortcut). Optionally, you also can enable "Backface Culling" to hide all surfaces invisible in Verge3D render.