What do I need for ALC (91B)? (Currently stationed in Italy)

You will need to have completed SSD2 for ALC. Depending on the NCOA you may be required to do an additional online phase. You can go to their respective website for latest packing list or call their operations directly. NCOA focus on general military doctrinal instruction and may have a MOS specific training embedded or in a follow on phase. All NCOES require a TASS and it requires your first line supervisor oversight and Commander's signature. Usually S4 handles your government travel, but there are many variables that may be handle by other shops. So when S4 said, "they handle it", then I would inquire to specifically what did they handle. S3 should be the bigger player in all this, but your company training/orderly room should be a liaison for you regarding schools and TDY travel. I would ensure your leadership is in contact with the Schools NCO because many installations have additional requirements. You must have an ATTRS reservation and you and the command will get an email notification. I hope this helps.

I am going to ALC 91L course in FT MCCoy Wi, what do I need to be prepared for?

You should be receiving emails that will tell you everything that you need to know including the current prerequisites and links to other resources. Advise - when in the course, study hard to score high on percentile graded courses. A lot of the tests are go/no go, and working hard to trace your schematics correctly will help out with that. I earned the title of Distinguished Honor Graduate by doing so.