In Inventor there is an option when you select a component, in this case out of Toolbox that allows you to extract the standard part, or select "Custom" which allows you to make changes to the extracted part.

Don't really see a clean way to do this in Solidworks yet. What I did, which seems like a long way, is extract the part into my assembly, open it up, then save it as a copy to make my modifications.

Please tell me there is a cleaner, faster method.