I came upon this today and thought it might help someone else out.
We're upgrading to HRCM 4.7 using MyIT and wanted to add some custom images to our Solutions. You might already know to configure an image for a Solution you select an option from the menu presented on the "Image_Filename" file:
What you may not know is how to add a custom image to this list (because I couldn't find any documentation on it). All you have to do is add the image to the AR System Resource Definitions form (accessible via the midtier object list):
Once added here, the new image should be selectable from the menu, and thus visible via MyIT assuming you turned on images for HRCM.