According to a review on Amazon, the Grip IT analog stick covers used to add resistance or something on a video game controller does work on similar sized controllers including a Dreamcast. Before you come home with these covers from the store, don’t forget to stop by the hardware or hobby store for some washers or buttons. If you put on the stick covers without some sort of spacer, the analog stick on the Dreamcast won’t make a full rotation on the edges, instead causing friction between the controller edges and the rubber. Just apply a button (upside down of course) before you put on the covers and you’re good to go. It’s less hair-pulling than hacking in a Xbox 360 analog stick.
Random time: Grip It Analog Stick Covers on a Dreamcast Controller