I realize that there are several attic venting discussions taking place, however I have a specific question. I have a house that is 25 years old, with 2 X 4 truss and only has two small gable vents. Ridge vents would be easy to add, but how does one go about retro installing soffit vents when the attic has blown in cellulose insulation? Climbing around in the attic is out of the question.