Hi Mateo,
Although I don’t give support for this, you can add pronunciations to the English lookup list (but not any other languages) by editing the file in the bundle, if you are very careful to use working phonemes, match the formatting of other entries, and keep everything alphabetical. You can’t make changes to that functionality at runtime. There is no special reason that adding fake pronunciations wouldn’t work, but it makes more sense in terms of maintainability to do that via substitution at the time of detection (i.e. detect “bike” and process it as if it were “bicycle”).