Ironically, the old IBM mainframe "dumb green screen" terminals had that ability, but not HTML GUIs.
I believe that HTML5 supports not only limiting input text, but also (on mobile devices), the intelligent selection of virtual keyboards (numeric keypad pop-up instead of a full text keyboard).
Unfortunately, RichFaces 4 is still stuck on HTML4, I believe, so that feature isn't available. The best you could do is attach a JavaScript to the keydown or keypress event of that control. Do a web search and
you should be able to find examples. Look for "HTML numeric only input", since it's not specifically a RichFaces thing.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.