I have met with success.
I first used the shaving cream (cheap Barbasol) & moderately stiff brush method. That worked well at removing the old kiwi without stripping off the finish or dye.
I let them dry out for a couple days, then...
I went after them with a quick wipe-down with acetone. Nothing too crazy, I just wanted to be sure that whatever they came impregnated with from the factory was removed, as it caused my polish efforts on these boots to be sub-standard and to prematurely get messed up.
Dry for two days, again...
Gave them a good, generous slathering and rub-in with regualr old kiwi. Let them completely dry and suck up the kiwi. Then, a I went after them with a quality horsehair buffing brush.
Results: A better polish on them than I ever got before and it has lasted longer than ever before on that pair of boots.
I expect a shoe polish to be acceptable for about a week at my work, which consists of wracking my brain in front of a monitor. A slight re-buff every AM and then they are good-to go for another day.
Of course, I usually rotate boots to let then dry out a day between wearings.
Thanks for all the tips.