u need all the hacks for usb loaders (with the exception of a cMIOS, but I don't think that was installed using this guide anyways)
yes, it is possible to suppress the update without using priiloader hacks, but its a pain in the ass, and I don't recommend it, i will explain how to do it below, but I do not recommend any1 use this approach, but instead stick to the priiloader hacks
but basically, all the update does, is it checks a bunch of your IOSs (and boot2) to see what version they're at. If the installed version is => update version, that specific IOS is left alone.
If u were to change the versions of all the IOSs (or cIOSs) to be => the updated versions (ie. the stub ios versions) then ninty will think these installed IOSs are up to date (ie. stubbed) even when they're custom.
so this is how u would do this for ONE cIOS... for example we'll do 249
on the wii:
-install the cIOS using the installer (must have patched IOS36 and already have stub IOS249 removed)
-pack custom IOS249 into a wad using bluedump (non-fakesigning versions)
on the pc:
-open the bluedumped wad using showmiiwads, change the version number to be => the stub IOS version number (which can be found in many apps, including the database for NUS Downloader). In this case, change the IOS version # to v65280 or higher
back on the wii:
-install the version changed cIOS249 using a wad manager (YAWMM is recommended)
end result-- ninty updates will see your cIOS249 is at the right version #, and it will not touch this IOS in the event of official ninty update. If you do this for all your cIOSs (and cMIOS or non-stubbed IOS30 or IOS60 if u are using these) u will no longer get the update message. You're boot2 must also be updated to avoid the update message, this will uninstall bootmii as boot2 (if u have it installed), but it can be reinstalled to the new boot2v4 directly afterwards (the ability to install bootmii as boot2 does not depend on the version of boot2 u have installed, it depends on the version of boot1 installed)