Another option is to make a custom english.lang and define the path in there (Updating the appropriate custom config files to point to your new lang file). This allows you to put the entire conversion mod into one folder. I chose this method for my tetris mod as it made (un)installation trivial for me to set up and for the end user (zip/unzip/remove a folder), especially considering I was already using a custom language file to support the save-file naming.
Code from my modified english.lang file:
<RESOURCES>
<Directory Path="fonts/eng" />
<Directory Path="tetris_TDD/lang" />
</RESOURCES>
Of course, the trade of is that this is initially more work than a quick line to be added to the menu config file.