Homebrew and Macports

1) Safely install Homebrew into into its own directory (downloaded bottles will be downloaded into here)

cd ~
mkdir ~/Developer
cd ~/Developer
git clone https://github.com/mxcl/homebrew.git

2) To set up the symlinks without having to chown /usr/local, just use chmod o+w

sudo chmod -R o+w /usr/local

3) Symlink the Cellar from /usr/local to ~/Developer/homebrew. This is necessary so that installed bottles can reference Cellar correctly.

ln -s ~/Developer/homebrew/Cellar /usr/local/Cellar

4) Install the bottle, in this case I used erlang. Be aware that Homebrew will still create symlinks into /usr/local

brew install erlang

5) Now that the bottle is installed, change the permissions on /usr/local back using chmod o-w

sudo chmod -R o-w /usr/local

Note: When installing more bottles, just do step 2, then step 4, and finally step 5.