Launch Options on Steam Version of The Ultimate Doom Assistance

[Con-Rez]

Okay, so i'm trying to work on a modification around the classic doom games released on steam. To those who own the steam version of the game, you would understand me when I say there are two choices before launching the game.

You can either "Play The Ultimate DOOM" or "Launch Ultimate Doom with classic controls".

Naturally, I thought it would be pretty nifty, after installing GZDoom, to be able to launch GZDoom with the "Play The Ultimate DOOM" option, and the original DosBox release with the "Launch Ultimate Doom with classic controls" option. I thought this would be easy at first, just edit the .bat files that the game appears to use in the installation folder.

But, it's never as simple as that is it?

Now, i'm going based off of the assumption that ultimate.bat and ultimate + mouse.bat are the files that launch when I make the selection of which version to Doom I want to play, but it's somehow not.

Despite the fact that I got the .bat files to do the desired effect (ultimate.bat boots the DosBox version of Doom, while ultimate + mouse.bat launches GZDoom), I've discovered that steam ultimately ignores those files and launches directly through GZDoom (renamed to dosbox.exe). Even removing the .bat files from the installation folder still yields the same result.

Has anybody else done what i'm trying to do? Does anybody know how I can track the specific path Steam takes to launch Doom through those two initial control options? Is it impossible to do because it does what the .bat files do directly with no middle man? Any assistance would be appreciated.

EDIT: Strangely enough, Doom 2 and The Ultimate Doom seem to function differently when being launched on steam. I was able to achieve my goal with Doom 2 because it uses the .bat files that can be easily edited when choosing between the control options, but The Ultimate Doom's ability to skip those .bat files after choosing the desired set of controls makes this much more difficult.