Nintendo has released a web based version of MiiVerse. You are now able to use a computer or a smartphone to get access. Ironically the 3DS's web browser and the Wii U browser ( I dont see why you would try to use the Wii U Browser) do not work with the MiiVerse.  Instead the PS Vita Browser's is capable of allowing you to use MiiVerse on it. It's great when companies support each other like this.

psvitamiiverse

Source