Can someone explain for the thickos in the class how to do this?
Print out the test chart and stick it some something reasonably firm. Set the chart up so that it fills the viewfinder of the camera with your chosen lens. Try to ensure that the target is roughly parallel with the back of the camera.
Set your lens to its widest aperture, put the camera on a tripod and aim it at the target.
Format the memory card and use the menu system to navigate to
7D - C.Fn III -5 on page 211 of the manual
50D - C.Fn III -7 on page 180
Choose 'Adjust by lens' and press 'Set' (the button in the middle of the big dial) then press the 'Info' button. The lens you're trying to calibrate should have its name displayed. Use the big dial to change the value on the scale to -20, press 'Set' and half-press the shutter to exit menu mode. Manually change the focus so that the target is out of focus, half-press the shutter to focus then take a shot.
Press 'Menu', 'Set', 'Info' and change the setting to -15 then press 'Set'. Repeat the process for -10, -5, 0, 5, 10, 15 and 20.
You should not have 9 pictures. Upload them to your computer and check, at 100% zoom, which is the clearest.
You may find that there's not too much difference between three consecutive shots - in which case the middle of the three should be close enough. If there's a big difference then you may want to take more shots at intermediate vales. Suppose 0 is poor, +5 is good and +10 is poor. Then the ideal is somewhere between 0 and +10. Take more shots at +3 and +10 - compare them with the +5 and you should have a good idea which is the best setting.
Some people will go further and test every possible value. I've never found it makes that much difference if I choose +5, +6 or +7.
Once you've decided on a value don't forget to go back to the camera and 'Set' that value. The camera will remember it for that lens (or lens + TC combination). Then you can move on to the next lens.
I hope that's all right. I haven't stepped through it to check. But it should give you a good idea.