Maven Gigapult plugin build is under development, so it isn't published in any public repository right now. Also it it's build using a non-standard JRuby complete.
To install an appropriate JRuby complete, download the jruby-complete-jar from downloads section, and install it locally using this command:
mvn install:install-file -Dfile=jruby-complete-r5387.jar -Dversion=r5387 -DartifactId=jruby-complete -Dpackaging=jar -DgroupId=org.jruby
After that, download maven-gigapult-plugin-0.3.3.jar from downloads section and install it locally using this command:
mvn install:install-file -Dfile=maven-gigapult-plugin-0.3.3.jar -Dversion=0.3.3 -DartifactId=maven-gigapult-plugin -Dpackaging=maven-plugin -DgroupId=org.gigapult
That is really all there is to the Maven2 integration.
