Take a look at alltray; maybe it's your solution.
From its website:
With AllTray you can dock any application with no native tray icon (like Evolution, Thunderbird, Terminals) into the system tray. A high-light feature is that a click on the "close" button will minimize back to system tray. It works well with Gnome, KDE, XFCE 4*, Fluxbox* and WindowMaker*. Xmms is supported in particular.
These programs follow the usual GNU command line syntax, with long
options starting with two dashes ('-'). A summary of options is
-h --help | Show summary of options.
-v --version | Show version of program.
-d --debug | Show debug messages.
-s --show | Do not hide window after start.
-i --icon | Use a PNG image as an icon.
-l --large_icons | allow large icons (> 24x24).
-st --sticky | visible on all workspaces.
-x --borderless | Remove windows decorations border, title, frame... from parent.
-m --menu | Add entry "menu text:command" to popdown menu.
-t --title | Show title change for seconds. Probably most usefull for xmms.
-g --geometry | initial position. see man X.
Installation (command in a terminal)
sudo apt-get install alltray