Yep, it's possible. You would need to add some code that takes care of stopping and starting up the images again. Then you would need to call on that code in functions you assign to the event handlers of the slideshow. For example, if you name the function that stops the images as "stop", then you would set up the hover behavior like this:
document.getElementById("slideshow").onmouseover = stop;
Then you'll want to make sure the images start up again when the user takes their cursor off:
document.getElementById("slideshow").onmouseout = play;
Make sure you don't include parentheses at the end when specifying the functions to be executed onmouseover and onmouseout. By leaving them out, the browser treats them as references to those functions and assigns those references to the onmouseover and onmouseout properties, which is what we want.
There are better ways to do this, I believe the more proper way to add event listeners like this is to use the addEventListener function rather than just using an equals sign as I've done here, but I'm not sure whether it's supported by all platforms (ahem, Internet Explorer). IE does have its own method for doing this though, I'm just not sure what it is. Anyway, the advantage of doing it using a function like addEventListener is that you can store multiple functions to all be executed when a certain event happens, rather than just one, which is what using the equals sign will do. I'm used to handling events with the jQuery library, which would do the same thing as the code I've written above like this:
...but you can ignore this last example if you're not familiar with jQuery.
Hopefully one of these methods of getting this done will work for you.