shouldnt be hard at all, as long as you know how to write code for that (i take it you do).
depending on the pack (i havent used sunset before) you can edit it either in theme.php or if there is a header.html . in theme.php, look for:
Code:
function themeheader()
or something close to it. if you know html, youll see from there where you need to add the menu line. if not, ask somone to take a look for you and write it out.