Close all door and windows to the room, leaving them open may caused soot to be drawn into the room.
Dust sheets to the floor area, the ones with the spill protection would be best.Tape dust sheets to the walls, floors(use masking tape) leaving just a small opening for the rods to be added, also insert a vacuum cleaner hose to suck up most the dust, gradually clean the flue by adding more rods and pulling/pushing the brush, keep going till it goes stack and if possible get someone else to go outside and look to see if the brush has popped out of the chimney stack, when the complete length of flue is brushed, slowly withdraw the rods wiping them as they are drawn out of the dust sheet seal, once all the rods are out and your left with just the brush in the fire place, do nothing for ten or so mins and have a cuppa, make sure vacuum isn't over heating.
If you leave the room make sure you've no soot on your clothes that may fall off as you leave the room, to clean up tap the dust sheet so most the dust falls off it, then un tape the bottom of the sheet and slowly empty the fire place of soot, it's very light and dusty so will blow about if you're not gentle with it, onec you've removed the majority of the soot, peal the tape from the walls and fold the sheet in over it's self so the dusty side is wrapped inside, roll up and place in a bin bag and set aside on the floor sheet.
Vacuum the remaining soot from fireplace including fire back and sides, beware of the direction that the cooling fan on the vacuum is blowing.
Vaccuum any soot from your overals and remove all dust sheets from room, wrapping rods and brush in the floor sheet.
Shake out all dusty things with the wind in the right direction, with your neighbours property in mind.
Wear overals and dust mask and when adding/removing rods keep a good seal on the sheet.
I'm not a sweep but have used this technique many times without the need to clean the whole room afterwards.