Setting up the button:
1) start javafibs
2) click on the "Preferences" menu
3) select the "Programmable Buttons..." menu option
4) in the "Programmable Buttons" dialog, type "tell repbot ask %Player"
5) in the pulldown box on the left, select the icon you want for the new button
6) click the "Add" button
7) click the "Ok" button
Using the button:
1) Select the Players tab
2) Select a player
3) click on the new button
4) view the results in the lower left text window
I tried to set one up for an %Inviter, but I couldn't get it to work

Hope this helps.