I did one on my '92 a few years back.
I had to pull the entire dash out.
It wasn't really very hard to do, but it took a long time and had a lot of steps.
I documented a lot of the job, but never did a write-up due to how many changes were made to our vans over the years.
Some notes that I remember:
The gauge cluster surround and the cluster itself had to be removed.
The steering column had to be loosened/dropped a little for the dash to clear (and I think the shifter had to be pulled down to its lowest point).
The climate control module had to be removed from the dash and pushed through the hole.
The radio had to come out.
The headlight switch had to be removed or unplugged (your choice).
There was some goo from the factory covering the 3 nuts for the heater box in the engine bay (there was also a bolt from inside the cab).
The accumulator for the A/C made working with the heater hoses difficult due to tight space.
The heater box was held together with 10 or 12 screws.
I figure a lot of the process is similar between our vans, but I don't know what all the differences are.
I had the same issue getting help that you're having, and ended up just jumping in and doing it.
I would suggest taking pictures as you go so you can remember how things go back together.
It's a big job, but it goes back together MUCH faster than when you pull it apart.