Just by adding the two elements horizontally each side of the base of the antenna for about a foot and then raising vertically and hanging at the top you have the two extra bands.
Pictures speak louder than words so I've added some for you to see just how easy it is.
The basic set up with the elements on each side of the antenna
A better view of how the elements are spread out from the base
And finally how the tapping was done with a simple screw, easy!
Overall I checked it against the cobweb as the moxon is currently in the lowered mode, it actually seemed quieter with roughly similar SWR readings. I think for some DX work it should be OK.