I've removed cabs using a lift on a crew cab or a few guys on a std. cab.
Doing a crew cab alone is a new one for me.
One way (although I've never tried it) would be to unbolt everything then jack up the truck frame as high as you can with a floor jack. Place some support under the rockers such as stacked up railroad ties,spare tire +rims,tall truck jackslands,etc. Just make sure the cab is supported safely and that the load is spread out on the rocker.
Now remove your tires+rims and bolt on some spare rims with no tires. Lower the truck down and roll the frame out from under the cab.
Like I've said, I never did one this way but I'm sure if you get creative it can be done.