On my system I enabled the TBB and IPP with the following command from the build directory:
cmake .. -DWITH_TBB=on -DTBB_INCLUDE_DIRS=/opt/intel/tbb/include -DTBB_LIB_DIR=/opt/intel/tbb/lib -DWITH_IPP=on
Notice that I had to specify the include and lib directory for the TBB while for IPP the CMake manages to find the same directories by itself. Note that this change is needed only for IPP 7.x users.
You can download the OpenCVFindIPP.cmake file with my modifications [HERE]. Beware, I am not sure that such modification will work on Windows or Linux systems!
UPDATE: I found that you need to set also the environment variable IPPROOT. In my case it is: export IPPROOT=/opt/intel/ipp
