you could subscribe to a vps and install os x server and a wiki on it and access that over the internet, but if you can't change the settings on your router you'll never be able to host something from your home over the internet.
you could also set up a vpn on that server and vpn into it, although you don't have to vpn to use the wiki.
i don't know of any isp that has their own router outside a client's home but if that's the case the only way is to host from somewhere else, like macminicolo.