Is there a reason you need the 2.4.6 version and not the 2.4.7 version? Else download it from main page here which contains all stable releases.
You could also download a git client and pull the latest master release from the corresponding github repository: https://github.com/Itseez/opencv.
- Master branch contains all new functionality that will be included in the 3.0 release
- 2.4 branch contains the latest developments and fixes that where merged after the 2.4.7 release
