Here's a couple pictures that show I've done this in the past:
Of course, few people have access to such luxuries. My father-in-law owns a monument company and uses the truck in the second pic for moving big slabs of granite.
Depending on how much room you have to work with, you could do it like this:
Get the cab disconnected. Tilt it forward and slide a 12' 2x4 or pipe under the back side, about where the rear cab mounts would be. Then tilt it backward and stick another 2x4 or pipe under the front end. Then you and three buddies will each lift one corner while a fourth rolls the chassis out from under it and then runs back and sticks a sawhorse or 55-gallon drum under each corner.
...or if you're ambitious, you could rig up a hoist (gantry) like the one it the following pictures. I saved this from a user's gallery at HotRodders.com:
Harbor Freight has a gantry similar to this, but at almost $600 it would be kinda hard to justify it's purchase for just one project.
CLICK HERE to take a look at their version.
I've also heard of people who have simply used a common engine hoist. After the doors are removed, you simply stick the boom into the cab and rig up some slings to attach to each corner and lift it that way.
