This won't work with the standard "WoW UI" party frames as they are not displayed in the same order across all sessions.

The reason we use addons, such as pitbull, to do this is that you can display all members (including "player") in the party and then sort them alphabetically. Once you're set up like this you'll get the same party display across all of your windows.

Technically, if you don't feel the need to see the actual health bars of the toon you are healing, you can place the clickbar area over anything that would normally allow you to target something by clicking, and, something that is displayed in the same position (and order) on all of your slaves.

I've not tried it with the Jamba display, but it's easy to test.

1) Clear your target.
2) Hover the mouse over the UI element you're thinking of using.
3) With the cursor still there type into chat "/target [@mouseover]"

If the target changes as expected, then everything should work fine.

=D