Broadly speaking, it’s fairly easy, as Italian uses the same vowels as in Hebrew (in fact, it’s a common way of explaining Hebrew vowels to English speakers). By default, the /a/ sound is assumed, and the /i/ sound is indicated by using a yod as though it were the letter i in Italian. If the vowel is an /e/, /o/ or /u/ sound, use niqqud to state a ségol, ḥolam, or shuruq, respectively. However:
- If the word starts with a vowel, use an aleph to “carry” it—e.g. אוניברסיטה
- If the /a/ sound is at the end of a word—e.g. università—indicate it with a héh sophit (e.g. אוניברסיטה)
As for the consonants:
- Use tet (ט) for all t
- Use samekh (ס) for all /s/-sounding s (e.g. sì – סי), zayin for all /z/-sounding ones (e.g. Pisa – פיזה)
- Use tzadi (צ) for all z or zz (e.g. pizza – פיצה); tzadi-apostrophe (צ׳) for ci or ce (e.g. città — צ׳יטה)
- Use nun-yod to represent gn (e.g. gnocchi – ניוקי)
- Use lamed-yod for gl (e.g. figlio – פיליו).
- Use shin-yod for sci (e.g. sciare – שיארֶה)
I think that covers it. If I think of anything else, I’ll add it in future edits.