You can add a reference to an image in item maintenance/inquiry.  Tab 2 additional, right side about half way down.

Looks like you can can get it to display the image link by using custom office to add it to the grid.

You might be able to create a button to actually display the image similar to what is in item maintenance but that would probably require a user defined script to accomplish.  Never tried so I don't know the details of that.

In the long run it might be easier to click on the item inquiry button on the order entry screen and then go to tab 2 additional.