I don't have a real straight-forward answer for you but I'll try to get you going in the right direction.
Open a terminal and su to the root account. Type in this command:
tail -s 3 -f /var/log/messages
Now insert the card into the reader and plug it in. Usually, on my system, the first device that usb gets attached to is sda1. You should see some info pop up within 3 seconds and it will indicate where the card reader can be found. Hopefully, anyway. Then you could:
mount /dev/<something, maybe sda1 like me> /mnt/usbdrive
Just make sure you have a mount point:
mkdir /mnt/usbdrive or whatever you like.
I hope that helps.