The spelling of the word "ITOO" is actually quite straightforward when using IPA phonetic transcription. The first sound is "i", which is represented by the symbol /i/. This is then followed by the sound "t", which is represented by the symbol /t/. The next sound is the "oo" sound, which is represented by the symbol /u/. Finally, the last sound is "o", which is represented by the symbol /o/. Therefore, the phonetic transcription of "ITOO" is /i tu o/.