There is no inbuilt method to do this, you will need to do it yourself. There is however a "Site integration" mod which should help you sort it out. Try searching in the MOD W/Code forum or checkout www.snitzbitz.com
My son's favorite show....lol Just so you know all I did was use the Site Integration mod and then choose footer and head to be included. Within the header I created a table (with whatever dimensions you want) and created an empty <tr> and an empty <td> Then in the footer I began the footer with a </td> and a </tr>. Basic look like this: Header: <table width ="640" cellspacing ="0" cellpadding="0" border="0" align="center"> <tr> <td height="480">