please see about cutting out a section of the floor.. and remounting the hoist.. huge hint.. have the guy cutting the concrete floor make 2 cuts.. the inner cut all the way thru.. the outer cut an inch or inch and a half larger only part way thru the concrete.. when the center is removed.. use a hammer and knock off the part way cut thru section to leave a step for the new pour to rest against the old without settling.. do use a post hole shovel or fence auger to dig down several feet directly under where the post will be installed.. driving some rebar thru the bottom of the dug hole also helps it is much cheaper to fix the floor than have this happen http://i.imgur.com/lje8zle.jpg

if a rush job is needed.. there is special concrete available used for fixing freeways that can be driven on in 4 hours. sets hard in 10 to 15 minutes.. so don't waste a lot of time mixing. 3/4 to 1 inch aggregate does not effect cure time and reduces amount needed but make it hard to drill for fasteners sometimes.. just thoughts.. also make the new pour at least 10 or 12 inches thick.