I watched an oil change for a 2009 Honda Shadow Aero on YouTube a few months back. If you type "2009 Honda Shadow Oil Change" in YouTube's search, it should come up. I'm not sure if everything would be the same, but it might help.
When I've taken the chrome side cover off my engine (2009 Honda Shadow Spirit 750) there is a pin/clip that holds the cover on along with an Allen bolt. It's tricky the first time because it's hard to see, but I eventually got it. There is a washer that goes with that clip too. I'm not sure if this is the "pin" you are referring to. By removing this particular cover, it does make seeing the oil filter easier but at least on my bike, it's not necessary to take that cover off.