import ij.IJ;
import ij.Menus;

import java.awt.MenuItem;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

class SplitChannelsListener implements ActionListener {
	public void actionPerformed(ActionEvent e) {
		IJ.run("Split Channels");
	}
}

splitChannels = new MenuItem("Split Channels");
splitChannels.addActionListener(new SplitChannelsListener());

Menus.getPopupMenu().add(splitChannels);