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If the size of the textures will remain unchanged you can try using the reimport feature of quickbms.
It uses the unpacking script for repacking.
Read the
3) Reimporting the extracted files
section in quickbms.txt.

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I don't have the time for making video tuts, sry.

Try to repack unchanged files. It should result in an archive that's identical to the original.
(for checking use fc /b newlyPacked.ipk original.ipk in windows console or any hexeditor which allows file comparison)

If there's a difference the unpacking feature probably doesn't work with the script.