This program can decompress and dump Zelda's graphics, so that they can be modified by your SNES tile editor of choice. The program can then be used to recompress and insert the graphics back into the ROM. It's very similar to what Lunar Magic does with SMW's graphics, just without the GUI.
Instructions on using the program are within the readme.txt file included in the zip file.
Zcompress - Zelda 3 Compression Tool (WinZip File)
Size: 98K zipped, 194K unzipped
Minimum OS (32 bit): Win95
Minimum OS (64 bit): WinXP 64
Updated: December 25, 2015.