Yes you can. There are a few different things that you will need to do so I will go over them one at a time.
1. The first thing would be to locate your rs-485 dongle that came with your camera. It should look like this.
2. The next thing to do would be to make sure you have a length of 2 conductor cable (you should be able to go up to around 4000 feet (using rs-485)
3. Connect this to the dongle from step 1, with the red (positive) connected to R(+) and the black (negative) connected to T(-)
4. Connect the other end of the wires to the joystick in the 485+ (red) and 485- (black) spots.
5. Now, make sure your Camera is set to be in Pelco-D and rs-485. This is done using the dipswitches on the bottom of the camera. If you have a HUddlecam 3x, 3xG2, 10x720, or the 10xG1 the dipswitches should look like this.
Switch 2 in the SW2 bank turns the camera from rs-232 to rs-485 which is better to use when using Pelco-D. Switch 3 in the SW2 bank switches the camera from VISCA to PELCO-D.
If you have a 10xG2, 3xWG2, 20xG2, or a 30x, your dipswitches should look like this. It's kind of hard to see, but switch 2 is turned on in the picture. This makes the camera rs-485 as well as Pelco-D.
6. Now you should have your camera hooked up to your joystick, and the last step would be to set up your joystick to be Pelco-D.
If you press 1000 + preset on the joystick, that will get you into the menu. Now go to KBD setup by pressing the "open" button. Under the protocol setting, change the joystick to be Pelco-D. Use the joystick to navigate down to the exit button, and then go down to the exit button again to exit the menu.
7. You should have total control of your camera using rs-485 and Pelco-D.