Note: Krita on OSX is very immature. These build instructions will give you an krita.app bundle you can package in a dmg and distribute. It doesn't use fink or macports: the goal is to have as native an application as possible.
You need to make sure you have cmake (2.8.12 or better), git and xcode installed.
Everything you do, you need to do from the terminal: you only need xcode for the compiler, not the ide.
Follow the instructions in krita/3rdparty/README.md to setup your build environment, Qt, the krita checkout, the dependencies and finally build Krita.