First of all, for Days, Hours, Minutes and Seconds to show on the same line, the dashboard will have to be expanded to at leaste 298px by adding the following css to your theme’s style.css file:
width: 298px !important;
Next, to force days to show on the same line as Hours, Minutes and Seconds you must add the following css to the theme's style.css file:
clear: none !important;
This will work fine if you are using the shortcode in a post or page like so:
[tminus t="12-12-2012 12:00:00" omitweeks="true"] as demonstrated here.
However, if you wish to have this displayed correctly in the sidebar, it will depend on how wide your sidebar is. For example, if your sidebar is 250px, then you will either need to use an image editing program to resize the background images, or use another, pure CSS style such as 'TIE-fighter' or 'c-3po'. Either way, you will have to understand a bit about how CSS works to make such changes.