This is a massive stretch but is the best idea I could come up with:
Explorer Canvas - https://code.google.com/p/explorercanvas/ - Implements the canvas in IE8 by abusing VML.
HTML2Canvas - http://html2canvas.hertzen.com/ - Can render your document onto a canvas, which can then be rotated.
Failing that, I suspect your only option is going to be to generate a rotated document server-side and give that to the client for printing.
Edit: One other last ditch would be to handle the printing via Silverlight, embedding the page in a browsercontrol inside silverlight (yuck), rotating that and printing the result via SL.
Really grasping at straws here though for anything client side in a legacy browser.