JDK 7 added a new transparency slider to the JColorChooser:

The proble
Although it's implementation dependent, you can remove concrete subclasses of AbstractColorChooserPanel by name.
This example removes all but the RGB panel:
AbstractColorChooserPanel[] ccPanels = chooser.getChooserPanels();
for (AbstractColorChooserPanel ccPanel : ccPanels) {
System.out.println(ccPanel.getDisplayName());
String name = ccPanel.getClass().getSimpleName();
if (!"DefaultRGBChooserPanel".equals(name))
tcc.removeChooserPanel(ccPanel);
}
This example restores the HSB panel:
for (AbstractColorChooserPanel ccPanel : ccPanels) {
String name = ccPanel.getClass().getSimpleName();
if ("DefaultHSBChooserPanel".equals(name))
tcc.addChooserPanel(ccPanel);
}
You'll need to determine the desired name(s) empirically.