Inside the untarred folder make a new folder called "release" (or any folder name) and run this command in it #"cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D BUILD_PYTHON_SUPPORT=ON -D BUILD_EXAMPLES=ON .."
the ".." will pull files from the parents folder and will get the system ready for installation for your specific platform.
in the release folder (#cd release) run #make
After about 3-4 mins (obviously could be faster on your machine) of make processing when its finished run #make install
That's it, now go to python and try ">>> import cv2" you should not get any error message.
I've tested it on python 2.7, should be virtually similar to python 3.x.