I have an A-element and I have put sIFR on this A-element. So, everything goes well, I can click on the sIFR element. But now I want to add a eventhandler to the A-element (onClick), so when I click on the sIFR element the javascript event handler will be fired. But I can't get it to work. Can somebody help me?
You can't just apply your JS to the A element (since it's being removed from the page and replaced with the flash it doesn't exist any more, hence, no JS gets triggered), you'll need to find a way to add it to the getURL(); that gets triggered from within the sIFR flash.
Doing something like <a href="javascript:alert('ZOMGWHAT!?!1!');">replaced by sIFR!</a> might work. (Though that gets into a usability/accessibility debate all it's own.)
It shows you how to create a "ghost node" (basically a clone of the A-element with the text hidden) on top of your sIFR Flash object. You can then apply the event handler to the clone.
The article is from a year ago, so the code lines he refers to are most likely different in the latest version of sIFR, but he gives a pretty detailed walkthrough of how to make the changes so you should be able to make it happen with the most recent version.