I just pulled a 6.9 at the local wrecking yard Sunday, with a T18(T19?) attached. Total project took about 4 hours I'd say - part of that was jacking the entire truck up because it had no tires and had sunk down into the earth a bit.
In that case, it was relatively easy::
1. Remove the fan and radiator
2. disconnect all the lines, wires etc. PS pump would stay with the truck, as would the AC, if you have it.
3. Pull front/rear driveline
4. Remove transfer case. Remove the transfer case shift lever from the transmission.
5. Remove gearshift(if applicable). On a ZF5, it's 4 metric socket head cap screws at the top, and the gearshift and "stub" comes out of the transmission.
On a 4-speed, there's a "dome" you unscrew, and the gearshift comes right out.
5. Deal with the exhaust. In my case, I cut the (non-turbo) exhaust where the transmission and transfer case meet with a sawzall.
6. Pull crossmember. This is the "hard" part, because the bolts are going to be rusty.
I used my DeWalt 1/2" 20V impact, 18MM socket, 6" wobble extension, 1/2" universal and 15MM wrench to get them off. All came off with the impact easily enough.
Once the bolts are off, jack up the trans a little, pull the crossmember.
7. Remove the 4 nuts holding the motor mounts in place - they are vertical in orientation(one above the other), 2 on each side.
8. Hook a chain to the motor and lift it up, slide forward a hair, lift and tilt it right out.
Now, you might have less clearance due to the turbo; might be an issue.
You can either remove the turbo, or remove the core support.
If you are into custom, you can simply modify it by removing the top crossover piece and make some brackets to reinstall it when you are done, for ease of motor removal/installation in the future.
Once it's out and clear, you can do whatever, reinstall it complete with transmission, and then just hook the transfer case up. Seems like a really good idea to me.