Download Eclipse 4.2 Classic 64-bits version from the Eclipse website. Extract the contents to a location, such as C:Eclipse. Adjust the eclipse.ini in that directory according to my post in order to pin it to the taskbar.
Next, within Eclipse, go to Window » Preferences » Install/Update » Available Software Sites » Add... and add the following URL under something like "4.2-M builds": http://download.eclipse.org/eclipse/updates/4.2-M-builds. After adding you can hit Reload to reload the information from the website. Exit all windows through pressing OK. Then follow up by going to Help » Check for Updates and you will most likely get an Eclipse SDK update right away. Accept the licensing terms and wait until it downloaded and installed everything and restart Eclipse.
Go to Help » Install New Software... » Work with, select the Juno entry and from the resulting list of software select General Purpose Tools » Marketplace Client followed by Next » Next, accept the license and Finish. Restart Eclipse when done. Now under Help is an entry called the Eclipse Marketplace.
Open the Eclipse Marketplace and search for and install the following: "code recommenders", "MercurialEclipse", "mylyn" (not selecting the Bugzilla connector). It might ask if it is OK to install unsigned content, acknowledge it.