Configuration of maven is done in settings.xml file. By default file is in %USER
Depending on the components used for creating custom policy you may need EE nexus credentials configured in your settings.xml file. In the servers section add a server element like in the code snippet below:
<servers>
...
<server>
<id>MuleRepository</id>
<username>NEXUS-USERNAME</username>
<password>NEXUS-PASSWORD</password>
</server>
</servers>