Editing drawable files in .apk files

[aufdemrand]

Looked on several forums, didn't see exactly what I was looking for..

Is it possible to edit any of the drawable files in an app I have installed? I have a nice audio manager, but I hate the image files that it comes with. I backed up the file with Astro, edited the png files on my sdcard, remounted and tried to back up with the edited file but it failed. I thought that would be too simple...

Any suggestions?