Script possible with PO RoG Landed Cost panel / table?

SOLVED

I am trying to script some sort of data flow from the receipt into the Landed Cost panel / table, but nothing seems to work.  I want to calculate a value based on receipt lines (conditional percentage), and write that value as a Landed Cost... without the user having to type it in.

I can get a line script to fire in PO_LandedCostReceipt but without being able to reference the Receipt details (or pass a pre-calculated value into the script somehow) this is useless to me.

Set/GetStorageVar does not seem to work (using oSession or oScript).

I can't find a way to open the main receipt object from within the PO_LandedCostReceipt script (eg. oHeaderObj gives an error).  Opening a new receipt object won't give me access to newly created receipts (only what's been previously saved).

Panel post load script won't fire, and even if it did I'd have the same problem with not having a pre-calculated value to write (or access to the receipt to calculate the value then).

Any ideas?