Custom Server Controls :: Access Multiple Header Rows Of The Gridview In Render Method?

I have extended a gridview to add an additional header with following two hyperlink controls "Select All" and "Clear All". These will operate on checkboxes in the data rows of the grid. I hide the column headers as I only want to show one column with checkboxes and "Select/Clear All" links. Everything is working as expected. Now, I wanted to add a scrollbar to my grid control, I did add the scroll bar using div but what it does is, it includes the "Select All and Clear All" links aswell. I only need to add the scrollbar to datarows and not to the header.I am trying to extend my control to include hte scrollbar by adding div during Render function. But how will I determine or loop through header rows? How will i get the header row with hyperlinks that I created above?? In Render if I do this.HeaderRow, it gets the original column header and not the custom header.