Hello,
You can achieve that by amending the CSS styles in your stylesheet. So for instance you can find
CMSTreeMenuLink,
subCMSTreeMenuLink,
CMSTreeMenuSelectedLink and
subCMSTreeMenuSelectedLink classes and add following properties definitions:
margin-left:20px;
display: block;
background-position: 2px 5px;It will make the link element as block element with optional margin and position of the background bullet image.
Anyway, I would rather recommend you going with CSS List Menu webpart if you want to play more with the menu design. This CSS List Menu uses unordered lists for the menu items which makes it fully CSS driven and easily manageable. Please take a look at following article for inspiration:
http://www.alistapart.com/articles/taminglists/Best regards
Ondrej Vasil