I have an Ender 5 Pro but it could be used for any box frame printer really. 

There's almost no clearance for the screw holes so you can have the mount as tight as possible to the extrusion and because of that you'll need to thread all screws into all holes.

You'll need the following to assemble:

2 M3x25mm screws to attach the extrusion mount to the caliper mount

2 M3x12mm screws along with 2 M3 T-Nuts to mount the whole thing to the X extrusion bar. 

The whole jig will give you enough clearance to not interfere with the belt but you should move the print head completely out of the way

CAUTION, if you accidentally hit home X or Z axis while it's attached, hit the power button IMMEDIATELY and remove it and move you print head once on again or without removing just move your print head out of the way again IF your printer allows it without homing.