Hi Jeff,
Here is why you can't find that option for the 7970 :(
Q: Which Cisco phones support the HHC standard?
A: HHC is a build in feature in the following desk phones:
Cisco Unified IP Phone 7975G
Cisco Unified IP Phone 7965G
Cisco Unified IP Phone 7945G
Cisco Unified IP Phone 7962G
Cisco Unified IP Phone 7942G
Please see attached (below)
Hope this helps!
Rob