First off - huge shout out to the author for the mod! Great work!

Secondly:
I have seen some people asking for Zedternal support in the comments, and AFAIK it does work for Zedternal, didn't do much testing but tried on the first monster and worked.

Go into Zedternal.ini
Find the line: Zed_Monsters=(MinWave=0,MaxWave=999,MinGr=1,MaxGr=2,MClass=Class'Zedternal.WMPawn_ZedGorefast_NoDualBlade')

Beneath that line paste this:

Zed_Monsters=(MinWave=9,MaxWave=999,MinGr=1,MaxGr=3,MClass=Class'zedcustom.bluehusk')
Zed_Monsters=(MinWave=20,MaxWave=999,MinGr=1,MaxGr=2,MClass=Class'zedcustom.bluescrake')
Zed_Monsters=(MinWave=5,MaxWave=999,MinGr=2,MaxGr=4,MClass=Class'zedcustom.greenbloat')
Zed_Monsters=(MinWave=16,MaxWave=999,MinGr=1,MaxGr=2,MClass=Class'zedcustom.redfleshpound')
Zed_Monsters=(MinWave=10,MaxWave=999,MinGr=2,MaxGr=3,MClass=Class'zedcustom.redhusk')
Zed_Monsters=(MinWave=24,MaxWave=999,MinGr=1,MaxGr=2,MClass=Class'zedcustom.redscrake')
Zed_Monsters=(MinWave=8,MaxWave=999,MinGr=2,MaxGr=4,MClass=Class'zedcustom.redstalker')
Zed_Monsters=(MinWave=5,MaxWave=999,MinGr=3,MaxGr=6,MClass=Class'zedcustom.magmaclot')
Zed_Monsters=(MinWave=7,MaxWave=999,MinGr=1,MaxGr=3,MClass=Class'zedcustom.shocktroop')
Zed_Monsters=(MinWave=12,MaxWave=999,MinGr=1,MaxGr=2,MClass=Class'zedcustom.hellfire')
Zed_Monsters=(MinWave=13,MaxWave=999,MinGr=2,MaxGr=3,MClass=Class'zedcustom.darkcreep')
Zed_Monsters=(MinWave=15,MaxWave=999,MinGr=1,MaxGr=1,MClass=Class'zedcustom.otis')
Zed_Monsters=(MinWave=11,MaxWave=999,MinGr=2,MaxGr=4,MClass=Class'zedcustom.sparky')
Zed_Monsters=(MinWave=20,MaxWave=999,MinGr=1,MaxGr=3,MClass=Class'zedcustom.honeybiscuit')
Zed_Monsters=(MinWave=20,MaxWave=999,MinGr=1,MaxGr=2,MClass=Class'zedcustom.revenant')
Zed_Monsters=(MinWave=14,MaxWave=999,MinGr=1,MaxGr=4,MClass=Class'zedcustom.mancubus')
Zed_Monsters=(MinWave=13,MaxWave=999,MinGr=2,MaxGr=5,MClass=Class'zedcustom.mrpelvis')
Zed_Monsters=(MinWave=18,MaxWave=999,MinGr=1,MaxGr=5,MClass=Class'zedcustom.prowler')
Zed_Monsters=(MinWave=26,MaxWave=999,MinGr=1,MaxGr=2,MClass=Class'zedcustom.baronhell')

Then you should see Zed values below, paste this next:

Zed_Value=(ZedClass=Class'zedcustom.bluehusk',Value=25,ValuePerExtraPlayer=2)
Zed_Value=(ZedClass=Class'zedcustom.bluescrake',Value=180,ValuePerExtraPlayer=18)
Zed_Value=(ZedClass=Class'zedcustom.greenbloat',Value=40,ValuePerExtraPlayer=4)
Zed_Value=(ZedClass=Class'zedcustom.redfleshpound',Value=300,ValuePerExtraPlayer=30)
Zed_Value=(ZedClass=Class'zedcustom.redhusk',Value=30,ValuePerExtraPlayer=3)
Zed_Value=(ZedClass=Class'zedcustom.redscrake',Value=250,ValuePerExtraPlayer=25)
Zed_Value=(ZedClass=Class'zedcustom.redstalker',Value=20,ValuePerExtraPlayer=2)
Zed_Value=(ZedClass=Class'zedcustom.magmaclot',Value=18,ValuePerExtraPlayer=1)
Zed_Value=(ZedClass=Class'zedcustom.shocktroop',Value=30,ValuePerExtraPlayer=3)
Zed_Value=(ZedClass=Class'zedcustom.hellfire',Value=100,ValuePerExtraPlayer=10)
Zed_Value=(ZedClass=Class'zedcustom.darkcreep',Value=80,ValuePerExtraPlayer=8)
Zed_Value=(ZedClass=Class'zedcustom.otis',Value=150,ValuePerExtraPlayer=15)
Zed_Value=(ZedClass=Class'zedcustom.sparky',Value=50,ValuePerExtraPlayer=5)
Zed_Value=(ZedClass=Class'zedcustom.honeybiscuit',Value=90,ValuePerExtraPlayer=5)
Zed_Value=(ZedClass=Class'zedcustom.revenant',Value=120,ValuePerExtraPlayer=10)
Zed_Value=(ZedClass=Class'zedcustom.mancubus',Value=60,ValuePerExtraPlayer=3)
Zed_Value=(ZedClass=Class'zedcustom.mrpelvis',Value=100,ValuePerExtraPlayer=10)
Zed_Value=(ZedClass=Class'zedcustom.prowler',Value=40,ValuePerExtraPlayer=2)
Zed_Value=(ZedClass=Class'zedcustom.baronhell',Value=300,ValuePerExtraPlayer=30)

Like I said I didn't do much testing due to lack of time. Obviously you should edit the numbers as you like to. The first bit you copy - determines minimum wave number and max for the monster to spawn, as well as min/max number of this monster spawning at once (group). If you want multiple groups of this same monster spawn at once just paste in the same line the 2nd time, you might want to edit the Min wave number tho so more monsters of the same type spawn later on as you progress through the game.
The second bit is dosh value you get for killing the monster and bonus dosh for each extra player, self-explanatory this one rly.

Would appreciate if someone could test this and edit the numbers for more balance, I might do myself if I find some time.

Cheers :D