Pidgin currently does not support Pidgin nativly on MacOSX. You can use Fink (or similar) to install the Unix version of Pidgin on MacOSX but you need X11 then and you don't have any real MacOSX integration.

Then, there is this inofficial port of Pidgin to MacOSX: ​https://sourceforge.net/projects/pidgin-macosx/

Currently noone of the Pidgin developers supports that project officially but it's right now the best (and easiest) way to build a native Pidgin for MacOSX.

To start, install Subversion if you don't have if yet and install Xcode.

You'll find everything you need in the SVN. Just check it out with this command in the terminal:

svn co ​https://pidgin-macosx.svn.sourceforge.net/svnroot/pidgin-macosx pidgin-macosx

Further up-to-date instructions for building can be found now in the file README.txt. Basically, you just need to install the frameworks (which are also there in SVN), just copy them to /Library/Frameworks/? and then you should be able to open the shipped Xcode project and just build it.