Breakpoint not working when debugging a plug-in

Title says it all: breakpoints in my IDEA plug-in don't appear to work. I hear it's because these plug-ins are running in a separate process and that there is a way to force that plug-in to run in the same process, but I wasn't able to find any documentation on how to do this (system property flag maybe?).

How do I get breakpoints to work when debugging my plug-in?

Thanks!