I've done that and it's not hard. Per the FAQ, remove glove box and lower panel to access the air plenum. Remove the blower. Use a vacuum to suck out what you can. I made a small hole in the plenum and inserted a narrow vacuum wand to be able to get the corners and bottom of the evaporator. Make sure you vacuum its face as well since mold grows there. While you are at it, spray with evaporator cleaner/mold killer to keep it cleaner and make sure the evaporator drain is free. Then tape over the hole and button it up. To limit future leaf intake, get some fiberglass insect screen and zip-tie it between your cowl leaf guard and the cowl opening. This keeps almost everything out.