I will assume that you have autofs and udev installed.
First of all, go to /etc/udev and create a file called usbstick.rules
The contents of that file are as follows:
This will create a symlink to /dev/sdX1 called "usbstick" with the group "usbstick" each time the usb device with the given product and vendor id is inserted. You can check the ids with "lsusb -v"
Remember to create a link from /etc/udev/rules.d to that file usbstick.rules
After restarting the udev daemon and inserting the stick you should see something like:
lrwxrwxrwx 1 root root 4 Aug 30 20:58 /dev/usbstick -> sdb1
brw-rw---- 1 root usbstick 8, 17 Aug 30 20:58 /dev/sdb1
So, we now have a link to the device that should be accessible to anyone on the usbstick group.
Only thing left is to mount the device. It can be done adding this line to /etc/auto.removable
usbstick -fstype=vfat,rw,gid=1004,umask=002 :/dev/usbstick
gid 1004 is the id for the usbstick group.
We will also need to create a link to the removable device, something like (from /)
ln -s /var/autofs/removable/usbtick usbstick
After inserting the stick and changing dir into /usbstick you should now see the contents of your stick.