While installing JBoss Tools 3.1 on Eclipse 3.5.1 and creating a update site, you can run into problem with network proxy (depending how's security set up for your web server), as it will ask for user & password to access internet to get in to JBoss update site (even if its local site). here's one work around of this problem, add this line in to your Eclipse.ini file (which is in under your eclipse folder) and restart eclipse. This should resolve proxy problem.
Set the following system property in you eclipse.ini file: -
Also, while doing some research on this topic, came across this site, which can be very useful for enterprise. So that you don't end up writing bunch of installation guide.