Looking for some help on a on join script

I can do the normal on join scripts easy ($nicks joins room and command is done) but I am stuck with if I join a room I want the script to check the nicklist for a certain username (username be placed in the script its self) and if the user was is the room it returns $nick is in $chan or if the user is not in the room it returns $nick is not in the room.

How do I get a self on join script to check the rooms nick list for a certain user, can this be done?

Hope this makes sense.
Thanks