1) JBossTools 4.0.0.alpha2 (http://download.jboss.org/jbosstools/updates/JBossTools-4.0.0.Alpha2a.core/) installs:
JBoss Tools Common - Mylyn 3.4.0.Alpha2-v20120922-0102-B38 org.jboss.tools.common.mylyn.feature.feature.group JBoss by Red Hat

2) But - Configuring JBoss Central (by adding this to the eclipse.ini file: -Djboss.discovery.directory.url=http://download.jboss.org/jbosstools/updates/JBossTools-4.0.0.Alpha2a.core/jbosstools-directory.xml) creates a download 'available site" of: http://download.eclipse.org/mylyn/releases/3.6

3) Installing the Mylin connectors through JBoss Central attempts to install:
Mylyn Commons 3.8.0.v20120612-0600

Which is ignored as:
"JBoss Tools Common - Mylyn" will be ignored because a newer version is already installed.