Hey, Mav!

Well, if you installed them into your D|S runtime correctly, when you click on the displacement map (Say 1x weak) it should upload them for you onto M4.

Go to your surfaces tab (mine is on the right side behind paramaters) and click on M4 in the tree-make sure all of M4 is highlighted.   Below the scene tree window there will be another where you can dial changes and add textures in the diffuse, gloss, ect areas.
Scroll down to displacement, and there will be a box below the dialer stating that the Displacement M4 file is there.

If not, you can click on the little arrow at the right side of that box for the drop down menu.  Find "Browse" and you will be given a pop up menu so you can search for the correct files.  Now, note here that if that is what is needed, you will have to select M4's Head, limbs and torso separately to do this to get the maps to work correctly.

You should be able to find the files in the Content>!Daz>Daz Characters>Mil_Man (or M4, not sure what that file is named (I'm at work here! ;) ) >Displacement> Head, torso, limb.

Then you can use the dialer to adjust the displacement...I keep mine to below 50 due to some lighting sets tend to add black pixels here and there through your textures if it's too strong.

You won't see the displacement, either, until you render-so you can do a simple pin light with raytrace or shadow mapping to see if it's at the setting you want.

Let me know if you need more help!

Dar