please see:
www.j-cook.pro/forum/12-new-functionalit...nu-a-title-icons#625
To change the images in the menu, you'll need to load the file: /administrator/components/[your_component]/[your_component].xml
In there, you'll find a an <administration> tag in which you'll find a <menu img> tag with a link/path to image as well as several <submenu> items (1 for each of your backend views.
To change both page and menu icons, I would recommend overwriting the images with your own - i.e. keeping the same file name and location so you can just upload them and not worry about renaming/linking anything.
Gez