Ankit Gajjar shares a Maya script XrayModeDisplay which can toggle Xray Display for individual objects in Maya, not just the entire scene. Check out the XrayModeDisplay for Maya to Set Xray Mode for Individual Objects in Maya here.
Ankit Gajjar writes: By default in Maya if you turn on Xray mode u will see all object in Xray. But with the help XRAY Script you can view any particular object in Xray mode in Maya. use Script Editor File > Load Script command to load script and then save in to shelf By using File > Save to Shelf command and name in xraymode and or use direct mathod of drapong and droping name of script to shlef with the use of command line To load a icon ____ copy icon bmp n paste it to script folder then go to maya and edit shlef then go to xraymode settings and navigate to icon.