The most important thing is that you keep the chain from falling off, and that the cams stay indexed on the chain the right way. You can put a zip tie or something like that around the chain to keep it from falling off. I haven't seen the wedge thing, but I'm guessing it's probably stuck between the outside of the chain sprocket and something else so that the chain can't slide off when it goes slack.
If you're unbolting the cam sprockets from the cams, and then swapping cams, put a heavyish zip tie through a hole in the sprocket and around the chain, to the sprocket is held securely and can't skip teeth on the chain. It's usually really easy..
Disclaimer: I haven't done SR20 cams, but they look pretty damn similar to everything else.