Make a whole and use the spray foam in a can
Blow in from the attic space is probably the best way. Anything else is going to involve changing interior or exterior surfaces.
Thank you very much!
Hi Jama. This job requires at least 3 people. Rent a blower to blow insulation into the walls from the attic. You will also need to purchase the packages of the insulation. One guy in the attic blowing the insulation with a very long hose. One guy to keep filling the hopper with the insulation, and one guy controlling the hose. I hope you find this useful. Good luck Jama.