Do this..
on *:nick:write nicks.txt $nick changed nicks to $newnick
Then.. make a popup that does something like this..
.Nickchanges:say $read(nicks.txt,$$?"=Enter a line")
Something along the lines of that. Everytime someone changes a nick, it's write a new line in nicks.txt like..
"Frog changed nicks to Magus"
"Magus changed nicks to Frog"
And so on.