To control the pronunciation of acronyms, the Cepstral voice engine allows the user to override the pronunciation of specific words on a per-voice basis. The mechanism involves defining a set of phonemes for the word in a user lexicon file. Please refer to our user lexicon page at:
http://www.cepstral.com/cgi-bin/support?page=lexicon
for the details (location of files, set of phonemes). The entry you need is as follows:
fyi 0 ah1 f w0 ey1 ay1
Note that all entries in the user lexicon must be lower case.