You need to use long screwdriver at least 12" long to get a decent attempt at idle adjust, I've found that using a 1/4" drive handle with a wobbly head extension bar with a screwdriver socket on the end works quite well too, you can get a reasonable eye line to the screw area from the front while feeling up from just behind the carb to guide the screw in place, practice when the engine is cold and you'll get a good feel of what you need to do while it's running