I don't think you can do that in a panel. If you want to add text to a link like that I suspect you will simply need to add separate launchers to the folders using nautilus.
There are several ways to do that in versions before 12.04, but I'm not sure how you do it in 12.04. However what you need is a nautilus.desktop file for each folder named the same as the folder itself, so try dragging a launcher for nautilus from the menu, then open the .desktop file it produces in gedit, which you will have to do by finding the real name of the .desktop file from in terminal. In gedit you can edit the name of the file and the exec used.
The file contains the following in 10.04
so edit the lines I show in red to point to the folders you want and name the same as as the folder.
Comment=Browse the file system with the file manager
Exec=nautilus --no-desktop --browser %U