The XXX4 sway bar kit has everything you need in the way of mounts and hardware, but yeah the bars won't fit at all. For the X - 5, a XX4 swaybar kit would work (I know they used to have one, don't know if its available any more) but most of us just make our own out of piano wire. Start with a .055 inch (1.4mm) wire, and just bend it as shown in the manual in the assembly of the rear suspension: pdf file found here:
http://www.4wdrc.com/pdfs/Manual-Page35.pdf