Although I haven't worked with the N64, I can say that Tile Molester is what you can use.
However, you will need to figure out which mode to use to view the graphics. I'm sure someone here knows.
Also, if you're lucky, the textures might use true 16 million colors, meaning you don't have to load a palette into Tile Molester to view them properly. If you are not lucky, you will need to hunt down the palette somewhere in the ROM.