I know nothing about this glyph, but, according to this reference, it doesn't yet have a Unicode value:
Without a Unicode value, it makes it hard to search for a font that might have it.
Two methods come to mind...
First is to enter the x and bar separately and kern them until the bar is where it belongs, but this is a bit clunky (though you could set up a GREP style to handle the kerning automatically). More useful, maybe, would be your very own font with the x-bar glyph. See http://www.indiscripts.com/category/projects/IndyFont where you can download the demo of IndyFont and make that glyph. It's an amazing product.