You could install pmount and add a command like
Code:
pmount-hal /dev/sda1 2> /dev/null
(change the device to match yours)
to one of your user's startup scripts. I recommend using Xfce's autostart script for this.
That method would use HAL for mounting the device as your user, which is basically what you do when you click on the icon.
The other option is to have it automatically mounted via fstab (which you said you didn't want) or you could have one of your boot scripts manually mount it using the
mount command.