It's pretty easy. Just download the most recent version of Dolphin (a dev build, 5.0-stable is way too old), get a NAND backup of one of your consoles, then go to Extras -> Manage NAND -> Import BootMii NAND Backup and import it. Then close Dolphin and open the Config/Dolphin.ini file in your Dolphin folder (usually under Documents), find the line that says "WirelessMac", and enter your Wii's Wireless MAC address there (seperated with colons, like WirelessMac = 11:22:33:44:55:66). You can find the MAC by going into the connection settings on the Wii, it'll be displayed somewhere.
Then open Dolphin again, and go into the settings again, go to the "General" tab, and enable "Allow non-matching region settings".
Then you can connect to Wiimmfi using a normal, patched image, which will probably result in another 7-day wait (due to a weird bug in Dolphin that happens most of the time after importing a NAND backup). Once that wait time is over, you should be able to connect without a problem.
Then when you are playing, just make sure the frame rate is high enough. Small temporary drops to like 58fps or so aren't a problem, but if you are dropping below 58fps you should decrease your graphics quality until you get full 60fps again. Although if you do get banned for having a too-slow Dolphin, it'll be a short temporary ban, so unless you get banned for that multiple times you won't get a permanent ban for that.