Yes, and it's easy.

Check the folder of your favorite skin in the blogs/skin directory. Assuming your skin is called "custom" there should be a subdir called "custom".
In this subdirectory you'll find a file _ main.php. (download it) and load it into your favorite editor.

Now you'll need to decide where to put it. Find the part under wich it will appear in the _main.php file and watch where that ends, this should be a </div> tag. Insert this code:

<div class="bSideItem">
<center>
<iframe src="http://rcm.amazon.com/e/cm?t=rttha00-20&o=1&p=27&l=qs1&f=ifr" width="180" height="150" frameborder="0" scrolling="no"></iframe> 
</center>
</div>

between </div> and <div ....> on the place you want it to appear.

Save and upload the _main.php to the right directory and youre done.

Good luck.

Wow. Easy! Thanks!!!