First apply the latest fix pack for your client version of ClearCase. Support for VS2015 may already be included.
If not, start with the approach IBM proposed for VS2013 http://www-01.ibm.com/support/docview.wss?uid=swg24036865
Before you run the scripts, be sure to replace all links to VS2013 ("12.0") with "14.0") in the provided packages and registry scripts.
Also, since you are probably using a 64-bit system, be sure to specify "Program Files (x86)" where necessary.
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