I took my old flourescent light fixture down in hope to replacing it with recessed lighting. The light that I want to replace is in my kitchen so I have no attic access. Here's the tricky part...after removing the old fixture, I looked into the ceiling & found that there is particleboard about 2.5" inches about the ceiling. Can I cut through the particle board in order to install the housing?

Yes you can cut into it, just make sure you do it slow just in case something is up there, when you are done, put insulation round it so cold don't come in and heat don't get out.