Worst can you open the ceiling 5 inches from the wall and work from there.
Running wires in insulated ceiling no attic.
New lighting cable computer networking and sound systems can all require wiring that may need to come through the ceiling.
There are two ways to insulate around wires.
Running electric across a ceiling sometimes requires you to enter into the attic but if you are lucky enough you may just be able to run the cable across the ceiling without setting foot in insulation.
On a single story home or the the upper floor of a multiple story home this means accessing your attic to run wire.
Tear the sheet across the width instead of tearing it lengthwise.
Cold cobweb filled crawl spaces damp basements and tight attics are all just a part of the job.
A 3 inch strip of drywall is enough to run receptacles around a room.
In addition your light fixture may require mounting to a ceiling joist or to two short blocks nailed.
For vertical work you can cut about 6 inches below the wall ceiling joint drill through the top plat and then fish from the opening ion the ceiling.
Running electrical wire through the channel between ceiling joists is generally easiest.
First you can tear or cut the insulation sheets in half and lay half behind the wire and half in front.
If the wire is too tight to the wall to make that easy you have a second option.