I don't know that a 30 is a 30 is a 30.
I think that the JK Dana 30 has a couple things that might be different - ABS tone rings? A different (encapsulated) unit bearing? Then again, you're only looking for the carrier and the spider gears, so you might be okay.
I'm not saying that you can't find a way to make a take-off work, just suggesting that it might be a bit more difficult than putting a TJ axle on an XJ.
Here's one other thing...he's already proven that he can do some pretty good damage to the Dana 30 on his 35's - maybe it's time to get a 44 under there? You can buy Dana44's that are bolt-on for a JK. Currie makes some VERY nice stuff - and they adress the biggest issue with the stock front JK Dana 44, which is the relatively small diameter tubes and the weak C's. I'd say look for a JK Dana 44 take-off, but nobody around here seems to be upgrading their JK front axles.