Is there a way to add a custom button in Google Chrome? I hate all the "Send to Instapaper" extensions in the web store, and love how the bookmarklet works, but I can't stand not having a favicon. Ideally, I'd just add a custom button next to the spanner in the top right, but I can't figure out how to do this. Even installing a custom extension would be fine, so if someone can point me in the right direction for that, that'd be great.
Here's the closest thing I've found (it's for Firefox, not Chrome):