I would probably put more options on the nick list.
As far as I know, you can't do anything to the nick list except change the color and font and width. Everytime I see a screenshot with a different nick list, there's always a dll behind it.
And then I'd probably make a command to control the nick list. Such as putting them in alphabetical order regardless of access. Or by using a $gettok() from the server via /names to list them in order from most recently joined and not. Then I'd know who's in the channel the longest.
The only way I see a list of that is my own /remainingusers alias. Or simply type /names #<Name of Channel>.