Need Help Replacing Main Menu Background Screen in MnLayHD.pac

[denbigh7]

I'm trying to replace a couple of the Main Menu background screens and having some trouble. 

The 1st one is this credits screen (below), which is in the DOTI file in the MnLayHD.pac file. I can extract the 1B59 texture file from the DOTI file and can inject a DDS to replace the background, and I can inject the 1B59 back into DOTI, but when I try to inject DOTI back into the MnLayHD.pac file, I get an error message. And it won't let me "compress and inject". Does anyone know the proper way to replace this file, or what I might be doing wrong?

The 2nd one I want to replace is the red background here, which is also in MnLayHD, in the EM00 folder, in the 1B59 texture file. I haven't even tried to replace this one yet, but I'm assuming it's the same as the one above. So again, I'd greatly appreciate any help on the proper method of replacing these. Thanks!