The best way to do this would be to take an existing report and modify it. For example take the reports under Historical Traffic Reports, for example "Average and Peak Traffic Rates - Last 7 Days". While in Design Mode, go to the Filter Results tab. Add in the following elementary conditions:
"Day of Week" is greater than or equal to "Monday"
"Day of Week" is less than or equal to "Friday"
"Time of Day [24 hour format]" is greater than or equal to "0800"
"Time of Day [24 hour format]" is less than or equal to "1700"
Keep in mind, you need to keep this report under your daily rollup time-ie, if you roll hourly data up into daily data after 30 days, the report will not have for you after 30 days.