This shouldn't really be in Server Fault, probably Super User or Ask Different, but you can install a lot of binaries by using homebrew, found here:
http://mxcl.github.com/homebrew/
Firstly you'll need to install command line tools for Xcode, which will probably require you to purchase it if you havn't already.
Once you've done this, run:
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
To install homebrew, then when it's installed, run:
brew install truncate