Well I need more information to answer your question best.
Do you load the nicknames into the dialog?
Do you select a nickname in the mirc nicklist?
If you select a name in the nicklist, $$1 will be the $nick.
You can also use $nick(#,N).
Returns Nth nickname in the channels nickname listbox on channel #.
If you use a mdx nicklist, line 1 is the control line so the 1st nick is actually line 2 so you would have to $calc and subtract 1 for the actual number in the nicklist.
After you have the nick, use $address or $ial to get the Ident and Address.