Different color & trend for data at specific starting point

[Steve]

I track (line chart) workhours for each day of the month. The last week of
the month a procedure changed. Can I have the last weeks workhours in a
difeernt color than the rest of the month ? And can I trend only a specific
portion of the month, such as the last 10 days of the month ? Could tect be
added to the data point on the chart where the change began, e.g. 7/25/07 ?

Thanks,