A sample maven plugin configuration with comments follows:

<plugin>
  <groupId>org.zeroturnaround</groupId>
  <artifactId>jrebel-maven-plugin</artifactId>
  <configuration>
    <!--
     If your project uses custom packaging that is not recognized
     set this to jar or war.
     -->
    <packaging>war</packaging>
    <classpath>
      <fallback>default</fallback>
      <resources>
        <resource>
          <!--
            A relative path.
          -->
          <directory>target/special-classes
          </directory>
          <!--
            You may use includes and excludes as with any other
            resource.
          -->
          <includes>
            <include>com/yourapp/include/package1/**
            </include>
            <include>com/yourapp/include/package2/**
            </include>
          </includes>
          <excludes>
            <exclude>com/yourapp/exclude/package1/**
            </exclude>
            <exclude>com/yourapp/exclude/package2/**
            </exclude>
          </excludes>
        </resource>
        <resource>
          <!--
            Empty resource element marks default configuration. By
            default it is placed first in generated configuration.
          -->
        </resource>
        <resource>
          <!--
            An absoulte path is used here.
           -->
          <jar>c:\projects\myProject\3rdpartyLibs\myLibrary.jar
          </jar>
        </resource>
        <resource>
          <jarset>app/3rd-party-lib</jarset>
          <excludes>
            <exclude>apache*.jar</exclude>
          </excludes>
        </resource>
        <resource>
          <dirset>c:\projects\project1Root\
          </dirset>
          <excludes>
            <exclude>**\build\classes</exclude>
          </excludes>
        </resource>
      </resources>
    </classpath>

    <war>
      <path>c:\projects\myProject\dist\myProject.war
      </path>
    </war>

    <web>
      <resources>
        <resource>
          <target>gfx/</target>
          <directory>c:\projects\myProject\static\gfx
          </directory>
        </resource>
        <resource>
          <!--
            Empty resource element marks default configuration. By
            default it is placed first in generated configuration.
          -->
        </resource>
      </resources>
    </web>


    <!--
      addResourcesDirToRebelXml - default is false
      Required if the resource directories are to be added to rebel.xml
    -->
    <addResourcesDirToRebelXml>true</addResourcesDirToRebelXml>


    <!--
      alwaysGenerate - default is false
      If 'false' - rebel.xml is generated if timestamps of pom.xml and the current rebel.xml file are not equal.
      If 'true' - rebel.xml will always be generated
    -->
    <alwaysGenerate>true</alwaysGenerate>

  </configuration>
</plugin>

Also, maven has a notion of build profiles that you can leverage.

    <profiles>                                                     
      <profile>                                                    
        <id>jrebel</id>                               
        <activation>                                               
          <property>                                               
            <name>env</name>                          
            <value>jrebel</value>                     
          </property>                                              
        </activation>                                              
        <build>                                                    
          <plugins>                                                
            <plugin>                                               
              <groupId>org.zeroturnaround</groupId>        
              <artifactId>jrebel-maven-plugin</artifactId> 
              <executions>                                       
                <execution>                                      
                  <id>generate-rebel-xml</id>       
                  <phase>process-resources</phase>  
                  <goals>                                        
                    <goal>generate</goal>           
                  </goals>                                       
                </execution>                                     
              </executions>                                      
            </plugin>                                            
          </plugins>                                             
        </build>                                                 
      </profile>                                                 
    </profiles>                                                  

Executing the example above with mvn -Denv=jrebel clean installcommand will trigger JRebel plugin to generate rebel.xml.