Once you have one router working, setup as many others as you need.
You should be able to connect one router to the internet and then be online from any other router.
The wirds.net project was designed for 8 routers, so any number between 1 and 8 should be easy.
When you deploy the routers, keep in mind that every router needs to be able to communicate with at least one other router.
There will also be some speed loss as traffic is 'hopped' from one router to another.
See Coverage and Speed for more information on the testing of the wirds.net 8 router deployment and testing.