Peaceful? Do you think "peaceful" protests actually do anything at all, politically? Do you remember the "million man march"? Do you think the hundreds or thousands of people that show up for anti-war, or anti-globalist protests accomplish anything? They do do not. Yes, they get media coverage. Sometimes they get tear gassed. But no traction. They are not effective. So why do you think you would be effective?
Well, I don't want to just bitch and not offer anything constructive. I have no idea if any of these ideas would work. But. It may behoove some folks with legal training to review the laws on the books to see if it is possible to:
(1) Somehow sue companies that hire illegals. Questions would relate to - do you have the right to sue? What is your "standing"? Areas of interest may be, that you are being harmed by a company that hires illegals just like you would be harmed by a company that pollutes. After all, the presence of illegals in a community can be statistically correlated with a higher crime rate and a higher drain on social services. Thus you may be able to show that you are being "harmed", in that your taxes go up.
(2) Related to the idea of how companies that polluted were dealt with before there were laws on the books banning their actions, it might be useful to see how those companies were sued before there were such laws.
(3) Extra-legal actions. What actions could be done against companies that hire illegals, other than law suits? For example, you might form a group in your town that agrees to punish companies that hire illegals in your community. Raise some money, hire a private detective service for 5 grand or so. Get the documented info - how many illegals, what shifts they work, get photos, etc. Hire a 2nd agency to vet the work of the first so that you don't screw up and "identify" someone as an illegal who is not. Then:
(a) Boycott the companies that hire illegals.
(b) Run full page ads in your local paper, with copies of the documented evidence showing that they are hiring illegals. Ask all the readers to boycott those companies.
(c) Make sure your "group" is incorporated as a nonprofit corporation so that the companies can't effectively try to sue you back as individuals.
Face it - if illegals can't get jobs, they won't come here.
On a side note related to the H-1B issue, you are free to use the database (its been posted a few dozen times) to identify firms that hire H-1B's. You are free to privately make business decisions not to do business with them. Even as an employee of a company -- as long as you make decisions in your own head, you can't be censured for them.