The only problem with texture pack unzipping is to do with the file structure within the zip file. And that is all down to the person releasing these packs. They will only be properly recognised if they are organised with the main folder name (nearly always the GOODROM name), and then maybe 1 or 2 subdirectories deep worth of folders. As long as the files within the first folder have the right code offset as the filename they should show up regardless of where they are within the directories. Also the game makes a big difference too lol.
The actual coding for hires texture extraction works but only when the folders are correct.