There is a new feature called 'Custom Imports' in beta 92. The idea is that if you have document formats not supported by TextAloud, you can hook in the document format if you have an external conversion program installed on your machine. The conversion program needs to be able to run from the command line, be able to convert the document format to text, and handle input/output file names on the command line.
So if you have documents with file extensions '.xyz' that TextAloud does not recognize, and you also have a conversion program that converts .xyz files to text files, you can set up a custom import provided the conversion program can run on the command line. The result is that .xyz files will appear in TextAloud File Open dialogs, and can be imported to TextAloud articles.
To set up a custom import, click Tools -> Custom Imports, and click the New Import button. On the new import dialog, fill in the 'File Extension' and 'Brief Description' fields. For the command line, enter the text string that runs the conversion program, using %InputFile% and %OutputFile% as placeholders for the Input and Output file names. TextAloud will fill these in when the custom import runs. %InputFile% will be replaced with the name of a document to import, and %OutputFile% will be replaced with the name of a text file to be created.
c:\MyUtilities\MyConverter.exe %InputFile% > %OutputFile%
The actual command line will depend on the conversion program, you'll need to check documentation for the converter to see how it expects input / output file names to appear on the command line.
The Custom Import feature is documented in the TextAloud online help.