I don't know if there's some easier solution, but what I usually do is :
Step 1 :
Create 2 character (lets say char#1 and char#2), with
different classes, on a server you don't play (I do this because I already use all my char slot on my server).
Step 2 :
- Start your game and get to the character selection screen, you should be positioned on char#1,
don't select char#2 yet!
- Have
Resorep save textures and then select char#2 on the selection screen. You can stop saving textures now.
- You should now have a set of textures in your resorep save folder including only the ones from the character selection of this class and starter armor, copy those into a separate folder (I named mine "Without")
Step 3 :
- Swap the starter armor of char#2's class to the armor you want to mod
- Start your game and get to the character selection screen, you should be positioned on char#1,
don't select char#2 yet!
- Have Resorep save textures and then select char#2 on the selection screen.
- You should now have a set of textures in your resorep save folder including the ones from the character selection of this class, starter armor
and the swapped armor, copy those into a separate folder (I named mine "With")
Step 4 :
Compare the content of your folder "With" and "Without" the armor you want to mod, the only difference should be texture from your swapped armor, get those out and work with it :)
(If you don't want to compare the content of the 2 folders manually, you can use some tools like WinMerge)
This method worked for the few armors I tried to mod.
Of course you don't have to repeat step 1 each time you want to mod a new armor...
Also, if anyone have an easier solution, please feel free to share.