IProjectDescription description = m_project.getDescription();
ICommand[] oldBuilders = description.getBuildSpec();
//
ICommand[] newBuilders = new ICommand[oldBuilders.length + 1];
System.arraycopy(oldBuilders, 0, newBuilders, 1, oldBuilders.length);
newBuilders[0] = description.newCommand();
newBuilders[0].setBuilderName(Constants.BUILDER_ID);
//
description.setBuildSpec(newBuilders);
m_project.setDescription(description, IResource.FORCE, null);
}