The custom text file must have on the first line:
WordList=some short title
followed by by a list of words or parts of words - each on its own line - that will sound the alert sound. For instance:
WordList=spanish camion tre malo
To load the file, go to the menu Bot item Word list, and select Load. Then search for the file and load it.
Make sure you have selected a wav file (same menu item, select Sound), and that no other wav file is running (de-select wavs in the aw browser).
If you wish to disable the file, chose Disable.