NOT A PROBLEM!
I have an easy setup that does the trick. All you need is iRotate, a wallpaper switching utility and some batch files.
1. Download the WallPaperSwitch-tool from here: http://planatscher.net/wallpaperhack/pivotwallpaperhack.zip
2. Extract the 4KB sized WallPaperSwitch.exe from bin\Debug\ into the iRotate-directory
3. Create a batch file (a simple text file with the ending .bat) with the following content:
iRotate.exe /rotate=90 /exit
4. Create a normal windows shortcut ON THE DESKTOP that points to the batch file. Right click and select Properties->Shortcut-tab. Change the Run-mode to Minimized. Put the cursor into the Shortcut-field and press your desired shortcut (for ex. ctrl+alt+right arrow). The Shortcut-field should now show your key combination.
There you have it. Repeat 3&4 for landscape mode by creating an another .bat-file and change it the /rotate=0.
Important: The shortcut file has to be on your windows desktop! Otherwise the key combination will not work. Read more here http://www.nilpo.com/2007/11/windows-xp/windows-custom-shortcut-keys-not-working/