Javascript Preload PDF File

I have embedded a pdf file into a website, and I'd like to show the user some sort of preload image while it's loading:

the pdf:

http://mikeandzachsbbq.com/Menu/

preload image I'd like to use:

http://audiadesign.com/preload.gif


When I made the preloader on audiadesign.com, it was for images, and here was the code I used:

if (document.images)
{
image1= new Image(783,198);
image1.src="http://www.audiadesign.com/images/1/1_02.jpg";

image2= new Image(783,198);
image2.src="http://www.audiadesign.com/images/2/2_02.jpg";

image3= new Image(783,198);
image3.src="http://www.audiadesign.com/images/3/3_02.jpg";
}


and so on....

Would it be possible to make a .js file that would preload the PDF file so that I could make the .gif image show up over that div onload until the .js loaded the PDF?

Thanks in advance
Chris