This is a longshot, and I expect someone will shoot it down, and is dependent upon having the caster kit and enough ceiling clearance inside the garage, but here goes...
1) Install the casters on the 4-post lift;
2) Lower the lift onto the casters so it is mobile;
3) Lift the end farthest from the door with an engine hoist, high enough to angle down the posts nearest to the garage door, enough so that they will clear under the 8' opening;
4) Carefully roll out the lift until the front posts are past the 8' opening;
5) Repeat on the opposite end to clear the other two posts.
Like I said, there's probably a reason why this won't work, but I didn't take the time to figure that out.
Ready...aim...fire!