I'm not sure what you mean by edit the text in the nicklist, but there are dlls available for modifying the display of the nicklist. Here is NickLust by Naru. There is also nicklist.dll by Epsilon which I think is available from mircscripts.org.
I want to replace one or more of the nicks in the nicklist with my own text, as part of a script I'm wirting that displays a name I choose for a person, not what their actual nick is.