You might find it useful to launch Flex Builder (as Eclipse plugin) help in a standalone mode by launching help in a mode that uses a standalone help server installed with the IDE.
To start standalone help, at the command line execute the following :
java -classpath C:\eclipse-SDK-3.2.1-win32\eclipse\plugins\org.eclipse.help.base_3.2.2.R322_v20061207.jar org.eclipse.help.standalone.Infocenter -command start -eclipsehome C:\eclipse-SDK-3.2.1-win32\eclipse -port 4567 -noexec
Open the web browser and goto http://localhost:4567/help/index.jsp