How do the ceiling guys attach the wire to the building supports without having to reach up there?
A tool is sold that goes on 3/4" EMT that allows you to reach up to the bar joists through the grid and twist on the tie wires.
That aside it is just as easy to make one.
We also have a long drill extension (about 12') that allows you to reach up and install drill tipped eye bolts on jobs that you can not wrap around a truss.
These work well in corrugated metal buildings with the perlins that support the roof deck.
Ideally you want to get them in before the grid as Greg said.