tedster - 7:30 pm on Jul 11, 2010 (gmt 0) [edited by: tedster at 8:10 pm (utc) on Jul 11, 2010]
Here's an overview of one approach. The details will vary according to the page template you are modifying.
1. Leave empty space in the layout flow, where the navigation div will finally appear on screen.
2. Place the code for the navigation div at the bottom of the body element.
3. Use the CSS absolute positioning rules to display that navigation div "on top of" the blank space you left in the regular flow.
You can research it here with our Site Search [webmasterworld.com] by looking for "source ordered content". If you want to track down one member, pageonresults has been a frequent poster on the topic.
I don't think the "source ordered content" approach is nearly the SEO help that it was a few years ago, by the way. I stopped using it, routinely at least, about two years ago.
This could make for a good new discussion in our CSS Forum [webmasterworld.com] so we don't hijack this Google SEO thread too far off topic.
[edited by: tedster at 8:10 pm (utc) on Jul 11, 2010]