You can't really force your currency upon others unless they are willingly enough to actually use the currency.
Make your currency worth spending for: make loads of shops with valuable goods for everyone to use; if one or two start to use it more will follow.
Beside mods that will probably roll out sooner or later; other than that try to spread your currency as far as possible with as many players as you can. Promote the mint, treasury,... so players actually know what's going on. I'm sure if there is a general town or a decent store set up you can easily spread your currency amongst the server population. A few alpha's back i once was on one server where we had one currency; it was the first and we were... 3-5 players; nobody else was using any other kind of currency so it doesn't make any sense to use anything else really so we had one global currency: it made the most sense. If your currency is the first; promote it on discord / in-game and i'm sure players will follow if you create a demand.
You can also make contracts which offer rewards (check the contract board) - in this case your currency - to start spreading it even more easily. Simple tasks can be performed: cut trees on your territory; hand in trees at stockpile X, get reward currency; be creative! :D