New to Modding -- Help Zipping into Iff

So basically I am trying to make a college hoops mod and I'm trying to edit the bootup.iff file, and correct me if I am wrong, but what I am supposed to be doing is extracting the iff from the 2k file manager, unzipping the file, then editing the dds files with photoshop, then putting them all together and zipping into an iff file and put it into the mods folder. I couldn't find out how to zip back into an iff file so I zipped into a zip file then changed the .zip extension into a .iff. But when I did and put into my mods folder, the game crashed on after showing the Tatum Cover. I also tried just putting them into a folder named bootup and my game still just crashed on startup.

Ive been trying to do this for the past two days so any help is appreciated!

Thanks,
mp14

Extract the iff using the file manager (of use a downloaded iff file)
Open the IFF file with 7-zip.
Drag and drop the dds file to your work folder. I usually keep my work organized so I can go back later. Even years later.
Edit the dds file. Photoshop or another graphic program.
Save the dds file properly using the correct format. BC1 or BC7, etc.
Some files may need the TXTR file edited. Uniforms need lines deleted. The TXTR file also shows the correct format. BC1 or BC7, etc.
Drag and drop any edited files back in to the IFF file. The IFF file is saved automatically.
Copy the IFF file to the MODS folder. Copy to the correct folder inside the MODS folder.

viewtopic.php?f=258&t=107952 Info is still the same.