Knock yourself out.
You will need to create a developer account on the Mozilla Add-ons site. If you then let me know the email address used for that account, I can then add you as an author for the Saloon Bar. This, in turn, will allow you to add new versions.
Obviously, you will also need to know how to develop Mozilla Add-ons. If you don't currently know then there are plenty of tutorials available online and the
Mozilla Developer Center isn't a bad place to start.
I would suggest that you make some changes to the Saloon Bar and then provide me with the updated version (contact details are in my profile). I can then check that you know what you're doing and add you as an author.
Sorry if that sounds like I'm making you jump through hoops but I'm conscious that any updates to the add-on will, potentially, affect a lot of people (8,399 active users at present). I feel some responsibility for making sure that I don't pass on the development role to someone who's going to break it for all those good folks out there.
With that said, thanks for offering and I hope to add you as an author in the not-too-distant future.