I don't know about hacking it from MEP itself (I've never tried it in MEP 2014 or earlier), but you might be able to do it with MAGIX Web Designer. I found this thread via Google Search, but the bad news (for me at least) is that it's in German. A few minutes with my translator indicates that it might be useful if you're really keen to do it.
I have had a look through the article pointed to by Terry, the technique is not applicable here - the DVD menus are not web pages and do not use HTML, Javascript, CSS and scripting.
. . . . Is there a way to edit / hack the options for the rollover effect for buttons in the DVD menu . . . .
Yes - when you get the full version with all the various templates you can change the button styles, text etc in the menu editor.
If you want to make your own, you really need to understand how the templates work and be prepared to spend quite a bit of time doing this !