You can follow the steps below or use a predefined script to perform them automatically (you need to adjust paths in the script according to your environment).
- Create an empty folder on a file system with 500M of free space ($M2E_BASE from here on).
- Download Eclipse 3.4 SDK and extract it into $M2E_BASE

Windows users beware of this issue with unzipping - Download and extract into $M2E_BASE/eclipse/dropins/wtp-3.0 the following components from Eclipse WTP 3.0 download page.
- Download Zest and Draw2D 3.4.0RC4 and extract into $M2E_BASE/eclipse/dropins/zest-3.4
- From $M2E_BASE/eclipse execute the following command to install AJDT 1.6
eclipsec -noSPlash -application org.eclipse.update.core.standaloneUpdate -command install -featureId org.eclipse.ajdt -version 1.6.0.200808282316 \ -from http://download.eclipse.org/tools/ajdt/34/dev/update -to ajdt-1.6
Because this is a dev update site, you may have to replace 1.6.0.200807041530 version with currently available. Check AJDT site.xml for the actual version - From $M2E_BASE/eclipse execute the following commands to install Subclipse 1.4
eclipsec -noSplash -application org.eclipse.update.core.standaloneUpdate -command install -featureId org.tigris.subversion.clientadapter.feature -version 1.5.1 \ -from http://subclipse.tigris.org/update_1.4.x -to subclipse-1.4 eclipsec -noSplash -application org.eclipse.update.core.standaloneUpdate -command install -featureId org.tigris.subversion.subclipse -version 1.4.3 \ -from http://subclipse.tigris.org/update_1.4.x -to subclipse-1.4

This update may get new versions upon new releases. Check site.xml for the currently available versions of org.tigris.subversion.subclipse and org.tigris.subversion.clientadapter.feature features - From $M2E_BASE/eclipse execute the following command to install Mylyn 2.3.2
eclipsec -noSPlash -application org.eclipse.update.core.standaloneUpdate -command install -featureId org.eclipse.mylyn_feature -version 2.3.2.v20080402-2100 \ -from http://download.eclipse.org/tools/mylyn/update-archive/2.3.2/v20080402-2100/e3.4 -to mylyn-2.3.2