Chart start time for overlap

I am looking to do exactly what the linked post below has accomplished, but I would like the overlap to have a set "Start" time that I can change. This way the overlap will not always start at 6AM.

http://www.excelforum.com/excel-char...-in-chart.html

Please let me know if this is possible.

I am also attached the sheet used in the linked post for ease of access.

The working bar chart is the bottom one.