Connecting a roku 3 to LSU's wifi

You're shite out of luck on a painless solution since Roku's don't support 802.1x, aka WPA2-Enterprise. You're going to have to use a workaround with another device that can access the network.

If you have a computer sitting around, you could always bridge the connection from it to the Roku since the Roku 3 has an ethernet port. I assume your computer would already be connected to the network so it should work. It's pretty simple these days if you're rocking any relatively recent Windows or OS X release.

If not, you could use an old shitty router or spoof a MAC address, but I'm not sure if I'd go through all that shite to avoid network bridging.