This program will download IOS37 from the Nintendo update servers, patch it, and install it as IOS249–making a completely functional “clone” of Waninkoko’s cIOS. This process does not involve any system-critical parts of the system, and should be completely safe. Of course, however, this software comes with no warranty whatsoever.

Also, if this applications detects IOS249 installed, it will attempt uninstallation.

http://www.wiibrew.org/wiki/Homebrew_apps/cIOS_Patchmii_Installer