If there's a channel installer app then it likely does not require you to provide a WAD as well, otherwise yes, you just install the wad with any wad manager. Obviously make sure you have brick protection in the form of Priiloader or bootmii boot2 before installing unverified WADs\Channels
Btw, ModMii comes with a nice looking spinning usb forwarder channel that will launch all 3 loaders, it will try gx first, if not detected it will look for wiiflow, and if not detected, it will look for cfg usb loader, and if not detected it will look for generic usbloader and usb-loader path\apps
this might not be ideal for you if you want to be able switch between loaders frequently, then you'd need more than 1 forwarder (or you'd need to use the HBC)