You can use a property set formula to refer to a block attribute. I have an example somewhere I can look for, or you can post your block if you are happy to.
If you still need to set the property set values through lisp you will need the AecScheduleApplication COM object installed. It was not installed as part of AutoCAD Civil it might be installed as part of MEP. You can just search for it in the registry to check.
To install it I just installed AutoCAD architecture (from my testing even the demo will work after the demo has expired).
I don't have much time to help at the moment, will do if I can.
Cheers, Rod,