mIRC doesn't let you sort the channel viewer list, unfortunately. You might be able to mimic it by making a script that parrots everything from #channel into @channel where you've created a sidebar viewer list that you can manipulate. But that would make it harder for scripts to work since $chan and # wouldn't exist in @channel.
I didn't say my way prevented nick changes, just that if a nick was set as white-on-white and that nick changed to another nick, the new nick is the same color without a script needing to paint it.
Channel modes are created by the network, not by mirc, but most 'real' networks have a channel mode, possibly +N, which lets the network block anyone in channel from changing their nick - though I think @ops can still change nick.
You can track nick changes like:
write troll.log $asctime Nick Change from $nick to $newnick $address