Your aperture will depend on the scene and the necessary amount of DOF that you need...you don't necessarily need to shoot with the lens at f/4.
1.) Set up and compose the scene, focus the lens (if using autofocus, set the lens to 'manual focus' after focusing). If your focus action is set to the back star button, no need to place the lens in manual focus mode.
2.) Determine a proper aperture to give the necessary DOF
3.) Set camera to manual mode and set the aperture you obtained in #2
4.) After metering the scene at the needed aperture, attach the filter
5.) Turn your shutter speed wheel 30 clicks to account for the 10-stop filter (assuming that your shutter speed wheel is set to the default 1/3-rd stops) If its set to 1/2-stops, then just turn it 20 clicks.
6.) Take picture. Rinse/repeat as necessary.
IMO, about the only time you'll need to calculate a shutter speed or refer to a chart is when bulb mode comes into play (shutter speeds longer than 30-sec). Simply turning the shutter speed wheel the 30 or 20 clicks is much easier and brainless and works whenever you're at 30-sec or faster. Plus, no need to fumble with a chart.
Some cameras that are equipped with Live View allow you to place the filter on the lens first and meter through the lens. The 5D2 will do this, and I've used this method with up to 12-stops (10-stop ND plus a polarizer) in good light. Can't say that the 60D LV will do this...best thing to do is try it out. No matter which method that you use (LV or focus/attach filter), shoot in manual mode. Av and Tv aren't very 'friendly' when strong density filters are in play.
