If you want, you can just get them out of the .dic file that is generated by LanguageModelGenerator at the moment – you have the path to it, since that is what you are passing to startListening:. The fallback generator is a word to phonemes function so you can just re-use its results.
However, you will get better accuracy results if you follow my advice from the blog post and seek out rhymes in the master lookup dictionary and do it manually.