Nice stuff Nitrobutler. I can offer another alternative, where you'll not have to worry about finding the centre. You can also use it to save it as an action to re-use at a later time as a dial creator too.
For this method we make use of some brush settings and the simple circular path.
First, create a custom brush in the shape of whatever you want as your dial - in our case, a rectangle. Then you can save that as a brush via "Edit --> Define brush".
Next, we change the brush settings on the brush palette. First, we remove the spacing setting in the brush tip menu. This then allows us to stroke only the anchor points of a specific path. Secondly, on the shape dynamics, we change the Angle control to "Direction".
Now, take the shape tool and create a circular path to the size of your dial. Then simply right click on the path, and select "stroke path" from the context menu. This will then stroke the four anchor points on the path. To move to another angle, simply hit (gently) CTRL+T or command+T to bring up the Free Transform selections. Keep holding the Shift button to allow a controlled rotation and rotate the path - or enter the degrees in the provided boxes. Then just stroke it again - you can alter the size of the brush for smaller notches, obviously. You can use the Shift+Ctrl+T command to repeat the transformation, as Nitro stated.
Ok, I did not offer a shorter explanation, but it's a useful technique nonetheless I reckon.
