See http://cloc.sourceforge.net/#custom_lang.
$ cloc --by-file-by-lang -read-lang-def=my_definitions.txt ~/github/uwsc/uwsc
4 text files.
4 unique files.
0 files ignored.
http://cloc.sourceforge.net v 1.56 T=0.5 s (8.0 files/s, 812.0 lines/s)