Key combos are useful and I think that is a good idea. Perhaps it might be a little difficult to add another key combo though, there are already quite a few. I think a checkbox to enable/disable is easiest with an alias that can do the same like many other features in mIRC.
I don't think that it's possible for mIRC to obtain the alt. nick of another user. I think this alternate nick list would only be able to show certain bits of information.
Besides, there's a high (majority) chance that this won't be included in mIRC. But who knows
Regards,
