If you are planning on occupying a building, you can't make mass public announcements of all parts of the planned action ahead of time. If you did, they would cordon off the building with the police, etc. so you wouldn't be able to get in to begin with. Take the building first, kinda "spontaneously" -- e.g., plan a mass rally (which should be the only part that is publicly announced), march to the building (hopefully with the media in tow), pile in under the pretext of presenting a petition or something, sit down, and don't move; and make rapid-fire announcements as soon as you take the building -- word-of-mouth, cyber-communiqués, etc. -- calling in more reinforcements and support from the local community and beyond.
In the year 2000, campus workers on strike and student and community activists in strike support occupied the OSU admin building for almost a month. We basically moved right in there, bringing in sleeping bags, a refrigerator, a microwave oven, a TV, a VCR, a laptop, etc. The then OSU president (a nice liberal man, from what I could tell) and other admin people basically stayed away from the admin building for the duration of the strike, conducting their business at the Fawcett Center (an off-campus convention center owned by the OSU). No one got arrested for the occupation, we had a great fun, and we contributed to a local class struggle a little bit.
Taking and occupying a building that is always guarded -- e.g., an important government building -- would be far more difficult. Shouldn't be impossible, though, with a sufficient number. -- Yoshie
* Calendar of Events in Columbus: <http://www.osu.edu/students/sif/calendar.html> * Student International Forum: <http://www.osu.edu/students/sif/> * Committee for Justice in Palestine: <http://www.osudivest.org/> * Al-Awda-Ohio: <http://groups.yahoo.com/group/Al-Awda-Ohio> * Solidarity: <http://solidarity.igc.org/>