You cannot change the internal programming to accomplish this, however you still have two options.
1) Contact NCH about the issue and they will work with you to modify the program to suit your needs (for a small fee)
2) Develop (or hire NCH / an independent group to develop) a plug-in for IVM which can send numbers (example 25) as a parameter, and have the plugin return the number in word form (eg twenty and five) and have the next OGM read the number to the caller.
The first way is by far the better option and will allow for more integration with the program.