WiiSCU...

I'm on 4.1. I want to be able to use the Shop Channel again.

Would I only need to update the Channel and NOT touch the IOS updates in this app? Just wondering.

Just update it. I'm pretty sure it will bring you to 4.2, but that honestly doesn't matter.

I just updated shop channel with WiiScu and it works now, but I'm on 3.4. I also had to update an IOS, don't remember which, but I think you will find this info on wiibrew.