I tested multiple options and played with them all on my Wii. These don't exactly do what the OP requested, but it does successfully hide HBC in a few ways.
a.) Cloak HBC, just masks HBC behind another channel. It still keeps a clickable channel on the menu but makes it appear as something else. (Simply, HBC with a banner of.. let's say, the News Channel.) HBC can be launched from BootMii, Preloader, (channel menu, obviously), and all means possible.. simply looks different.
b.) Super Cloak! same as above, but the channel looks like a blank channel slot (static tv set style.) You can still + or - through channels and find it, though. It hides quite nicely.
c.) Hide HBC. This basically installs a "hidden" channel that links to HBC. There is nothing to click on the channel screen. You can access it by the Preloader screen or an app with a HBC launcher (i.e.. USB Loader GX) The downside to this one is.. since there is no menu channel, it disables BootMii (from boot2) from accessing HBC.
d.) Use the built-in SD ghost file. In order for this to work, you can't run anything from the SD Card Menu (except HBC.) Just toss HBC on a SD card (obviously one you'll hide away, not the one you use normally) and run it from the SD Card. The Wii creates a ghost channel (you can see it in Settings > Data Mgt > Channels) This ghost will stay until another SD file is run (thus why you can only run HBC) or you run out of space (in which, it autodeletes to make room.) The ghost is viable enough to launch from Preloader and boot2 BootMii.
A, B, and C require some kind of wad tool. C requires a bit of knowledge to know how to break a wad from showing without it being a banner brick. D is completely performed on the Wii.
If you have forwarders for everything useful on the menu, and don't run anything from the SD card -- D is rather viable. Just remember that any of these doesn't prohibit launching HBC from another app that has a "launch hbc" option.