I hope you don't mind me throwing in my view here.
Personally, I think that MTW2 is the wrong platform for a W40K mod. I think that NTW is a better platform to use. And I think it would be best slotted in as a sub mod for the Great War mod.
Why - because there is already a WW2 sub mod for the Great War mod. And probably more importantly, because assets like tanks, machineguns, modern artillery, mortars, trenches etc are already created for the Great War mod. A lot of the requirements for a W40K mod are already there. They just need some modifications.
With a bit of imagination, and a few detail changes, some of the Imperial Guard regiments are already present in the Great War mod.
Imperial Guard, and Traitor guard for the enemy, would be good starting point.
Think about it for a while. I am sure it would constitute a good option.
Just my two cents worth. Being an old Imperial Guard devotee from way back, I would like to see this happen.