I wonder if it is posible to set a custom width and height on fancybox images?

As a standard, the width and height of the fancybox changes in relative to the width and height of the images, but i want to be 800 width and 600 height, at all images.

I want to create something familiar to the image-box on facebook, where you see the image at the left, and description and comments at the right.

Could be great if someone could help me with this... :)

* TheYaXxE