macqgis
I have installed the requirements:
and I've made sure these requirements are properly installed by checking library/frameworks and /Library/Python/2.7/site-packages.
When I go to install QGis I get an error message stating "The installation has failed. The installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance."
I am running El Capitan 10.11.
if you delete a particular plugin from .qgis and then QGIS works then I would say that the problem is in the 3rd party plugin, not QGIS. Drop a note the plugin author.
If you work on Mac OS X, you don't need to install PyQt or sip, they are integrated in the QGIS version of Kyng Chaos
QGIS use the Apple Python therefore you can use PyQt and sip outside QGIS with a simple sy.path.append
If you use the Homebrew version of QGIS, all is installed in /usr/local/Cellar with symbolic links in /usr/local/
Now, if you want to install PyQt yourself, it is not a GIS question but I assume that you use El Capitan and you know the problem of the System Integrity Protection (SIP) (explication of your errors, /System, /bin, /sbin, /usr are protected) and How to Disable System Integrity Protection (rootless) in OS X El Capitan
Best Answer
http://www.kyngchaos.com/software/frameworks notes that the frameworks are built for Lion, MT Lion and Mavericks.
So it seems that El Capitan 10.11 may not be supported yet.
Perhaps you should contact the maintainer, William Kyngesburye, directly about this issue.
The other download source http://qgis.dakotacarto.com/ notes that 10.11 is untested yet.