下面是官网的说明，基本上的意思下面有图片说明.
To install m2eclipse, use the following Eclipse update site to install the core of the m2eclipse plugin. This Core update site contains a single component: "Maven Integration for Eclipse (Required)". When you install this component you will be installing all of the core Wizards, the POM Editor, Maven Repository integration, and Maven integration
m2eclipse Core Update Site: http://m2eclipse.sonatype.org/sites/m2e
IMPORTANT NOTE: You cannot upgrade from m2eclipse 0.9.8 or m2eclipse 0.9.9 to m2eclipse 0.10.0. If you are running m2eclipse 0.9.8 or 0.9.9 you must either uninstall m2eclipse from your Eclipse installation or start with a fresh installation of Eclipse.
To install this plugin in the Eclipse IDE:
Select Help > Install New Software. This should display the "Install" dialog.
Paste the Update Site URL into the field named "Work with:" and press Enter. Pressing Enter should cause Eclipse to update list of available plugins and components.
Choose the component listed under m2eclipse: "Maven Integration for Eclipse (Required)".
Click Next. Eclipse will then check to see if there are any issues which would prevent a successful installation.
Click Next and agree to the terms of the Eclipse Public License v1.0.
Click Finish to begin the installation process. Eclipse will then download and install the necessary components.
Once the installation process is finished, Eclipse will ask you if you want to restart the IDE. Sonatype strongly recommends that you restart your IDE after installing m2eclipse.
然后就能用了~ M2eclipse的网址有可能常换，用的时候BAIDU一下~