You can see the hdr and rendering properties below. This is "mental ray" and in this scene, I used a skylight. I've also used the hdri for the enviroment. Using these properties, you could have a render in about 5-10mins.
Click to Enlarge
I have saved out the image as a "tiff with an alpha", after it had been rendered . Now its off to use Photoshop as its easier for creating the background
Open up he saved image and select the alpha channel in Photoshop.