Indexing Non-Standard Include Paths In Eclipse

If you are using software packages such as ROOT which tend to be installed in non-standard paths but still want your Eclipse IDE to index them (for handy code completion features and the like) here is how to do it.  Unfortunately I have not found a way to include these globally (please comment if you have such a solution) but for each project separately.  Right click on your project, hit Properties and select Paths and Symbols under C/C++ General (for C/C++ code).  In the Includes tab add the extra path for the appropriate language.