Steve did some interesting, but extraneous, things to get his mod working. There is actually an extremely simple solution that does the exact same thing, but with only a small single value change in one file.
* Throw out his mod completely and grab a fresh character_definitions.xtbl file.
* Find the StyleTest_PC entry and only change this one entry:
<Height>1.0</Height>
I did some math and found the values that should match exactly with his height mods (I tested them and compared screenshots to his to confirm) :
<Height>0.75</Height> Child
<Height>0.85</Height> Teen
<Height>0.90</Height> Female
<Height>1.15</Height> Brute
NOTE: His male version had no change
I believe that the entry below StyleTest_PC named StyleTest_PC_MP2 is for your coop partner, so if you want them to be the same height as you simply change the height value there as well.
Uzi, you should be able to simply apply this value change to whatever custom mod you are trying to use like GPO or Gandalf's one and make it work.