To move around in the ModelConverterX object preview you would use your mouse. With the left button you can rotate the object, with the right button you can pan the object. And with the mouse wheel you can zoom.
And to control how much zoom and pan you give there are two options: PanScale and ZoomScale. These can be changed to determine how much pan and zoom effect moving your mouse gives.
A while ago I also added a sensitive mode. This means that if you keep the S key pressed all rotating, panning and zooming will go with steps that are 10 times smaller than normal.
And from the next development release there is another way to move around in the preview. You can now use the keys on your keyboard as well. With the arrow keys you can move around over the ground plane. With the up key you go forward, with the down key backwards. Left and right obviously move you in those directions. And the page up and page down keys can be used to move up and down respectively.
Hopefully this new navigation mode makes it even easier to move around and inspect your models.