From the manual page (accessed 2016-03-10):
tlgu will convert an input_file from Thesaurus Linguae Graeca (TLG) and Packard Humanities Institute (PHI) representation to a Unicode (UTF-8) output_file. If output_file is not specified, the Unicode text is directed to standard output. The TLG/PHI representation consists of beta-code text and citation information.
(Untested. Software last updated 30-Mar-2012.)