src/it/system-scope-dep/pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project>
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.apache.maven.its.ant</groupId>
  <artifactId>system-scope-dep</artifactId>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <build.compiler>extJavac</build.compiler>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.apache.maven.its.ant</groupId>
      <artifactId>dep</artifactId>
      <version>0.1</version>
      <scope>system</scope>
      <systemPath>${lib.dir}/system-scope-dep-0.1.jar</systemPath>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-ant-plugin</artifactId>
        <version>@project.version@</version>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-antrun-plugin</artifactId>
        <version>1.1</version>
        <configuration>
          <tasks>
            <property name="lib.dir" location="${lib.dir}" />
            <ant dir="${basedir}" antfile="${basedir}/build.xml" target="compile" />
          </tasks>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>