And hope that none of the pins are rusted into place. Or for that matter, the gland heads.

i'd figure in about 12 to 16hrs labor for that.

the most intensive part being removing the primary boom to access that leveling cylinder (if it's the one stowed in the very rear of the primary boom tucked up inside there connecting the primary to the secondary it's called the Master cylinder in the manual).
If you have a way to support the boom you can also elevate it and block it up or if you have a crane you can use that with the blocks for support, once you get it up in the air you'll have clearance to pull the pins and retract the cylinder and pull it out. It just depends on how much work your willing to do. Of course the safest way is to remove the primary boom.
The oscillate cylinder should be fairly easy, just stabilize the frame so the articulating axle will not move, take the cylinder loose and activate the switch that triggers the leveling circuit and make the cylinder retract or move so you can remove it. There may be another way to get it out but that's just one way.
Repacking the cylinders isn't that hard to do once you get them off the machine and on a bench in a vise.