I downloaded the platform runtime binary (http://download.eclipse.org/eclipse/downloads/drops/R-3.4.1-200809111700/download.php?dropFile=eclipse-platform-3.4.1-win32.zip) from http://download.eclipse.org/eclipse/downloads/drops/R-3.4.1-200809111700/index.php, AFAIK it is the minimal eclipse installation that can update itself.

Then I registered the update site for JBoss Tools 3.0.0.cr1 (http://download.jboss.org/jbosstools/updates/development) and was very surprised to see that It "apparently" does not require to install the WTP 3.0.x. and I AFAIK it should be a requirement.