I used the following pattern found on Sony Blu-ray movies. It can be accessed at the menu with "7669 enter."
In the custom display mode my TV has lightly colored halos beside vertical black bars when sharpness is at minimum. What I did was to ramp up the sharpness until they went away, usually stopping at 22. Then I set sharpness too high, so that I could see the white edge enhancement halos, and ramped down sharpness until they disappeared, stopping at about 26. For the custom display mode, I split the difference and use a sharpness of 24. In standard mode the procedure resulted in a sharpness of 10, and I left vivid at minimum because it shows edge enhancement halos.
I have been using the Detail Enhancement set at medium, because it seems to create a more sharply defined picture without introducing too many problems. Looking at the test pattern, this feature seems to shift some shades darker while throwing out intermediate shades. At the higher settings, the blockiness and other anomalies it causes show up more in the test pattern. The following pictures are from the lower left circular pattern, and might give a sense of what negative effects Detail Enhancement causes if you don't have access to this pattern.
KDS-50A2000, Custom mode, Sharpness 24, Advanced Features off
Detail Enhancement - Medium
Detail Enhancement - Maximum
Detail Enhancement - Maximum, Edge Enhancement High
(This further exaggerates the changes Detail Enhancement causes for comparison)