jad, due to the fact that your boyfriend lives in Italy illegally, and you yourself are not an Italian national, what you are proposing will be very tough going, as I suspect you have already found out. The fact that the law firms you have contacted have turned you down, should give you a hint as to how problematic your situation is.
The best that I can do is to give you a link to law firms that handle immigration in Italy. Please scroll down the list:
Immigration Law Firms - Italy Immigration Law
Although I know you would prefer to live in Italy and not the UK, you might have better luck if you try for UK citizenship for him first. I would imagine if you both go to Tunisia as a starting point, that would be the way to begin your uphill battle. Possibly marry in Tunisia, apply for visa for your boyfriend to UK, work on UK citizenship. Then you both can work on visas and/or citizenship in Italy. Please discuss all the possible options and scenarios to ensure the outcome you wish for, with the solicitors you contact. They will be able to advise you better than I. You may also wish to contact immigration solicitors in the UK for advice as well. You really need to arm yourself with as much information, regarding your situation as you possibly can.
The best of luck to you both!
