With IPO v1.4(22) and Definity Handsets (6424D+), you could use the following for a DSS button;
Action = ForwardUnconditionalOn
Telephone Number = <Huntgroup Extn No>
Hence if the Reception is out for lunch, she could forward incoming caller to another huntgroup (eg Lunch). You will have a visual a green light on that DSS button.
Give it a try