You should be able to get to the Phillips head screw slightly sideways. Try poking around the needle housing in different directions. If you have a large Phillips screw driver, you should be able to get enough grip on the screw to get it off. It is not on very tight and doesn't need much force.

I haven't tried to remove the needle housing, but it should be relatively easy like your describe. Just write down the order in which you removed things and make a sketch of any settings that might be disturbed. Removing the crank case etc is no big deal and nothing will fall out (shine a torch in to check for rust while you are at it. Be careful to replace any gaskets on the needle houding.