Download Toadstool 64 (Mac OS X)
Downlaod Toadstool 64 (Windows)
Since Toadstool 64 is a program made both for Mac OS X and Windows, you don't need Darwine to run it on a mac.
These download links are the actual download links from the creators site.
To edit a Super Mario 64 Rom, you will need to download the Rom Extender.
Toadstool 64 is a Super Mario 64 level editor. To edit Super Mario 64, you will need a rom for it, which I cannot supply any links for due to law circumstances. You can edit x/y coordinates of objects such as enemies, hazards, trees, coins, blocks, and a bunch of other things. You can also choose what song you want to play on a certain level. You cannot put your own songs in. You can edit game textures by putting in your own images, and you can edit Mario's colors and size as well. To master this, you might want to go to Youtube and search for tutorials.