Hello! I'd like to help you with this usercript.
You did not provide details about the game and nature of the script, so I can't talk much about how I would do it. I do propose that we talk about it via chat carefully - then I will take a careful look on the game itself and what you want done, see if it's possible and tell you how I would do it; then we can actually award the project, if it interests you.
I have some experience with userscripts, but I have no published scripts to show you (I use it to make casual, simple improvements on sites I use). I do, however, have a lot of experience with Javascript itself - I've been a web developer for a decade already, and am very fluent with it; recently I've been using Javascript server-side with Meteor and Node to write corporate web applications. I have also have an interest on games and am generally very interested and familiar with how they work; this will likely help me on this job.
In short, I think I'm a good fit for your project, and am frankly quite curious about what you want done. I'd love to hear more about it.
Thank you!
M. Muller