That's where playing around with CSS comes in. I use Firebug with Firefox. With a little testing I came up with this code which MAY work somewhat for you but each situation is different.
You would put the following in the Configure Header Area box most likely right above %logo. The ID is arbitrary.
HTML Code:
<div id="top-phone">315.555.1212</div>
Then you would put something like the following in ATO>Add HTML/CSS Inserts>CSS Inserts
HTML Code:
#top-phone {
position: absolute;
margin-top: 50px;
margin-left: 800px;
}