Modify a Preference

This URL would modify the calendar preference ceBgcolor to have the value white:

http://calendarserver/set_useprefs.wcap?id=b5q2o8ve2rk02nv9t6
&set_attrs=ceBgcolor=white

This URL would allow the logged-in administrator to modify the calendar preference ceBgcolor to have the value black for user jdoe:

http://calendarserver/set_userprefs.wcap
                     ?id=b5q2o8ve2rk02nv9t6
                     &userid=jdoe
                     &set_attrs=ceBgcolor=black