Hey Kevin I took a quick look. Have NOT tested this but here a couple things that might help.

1) If you do the OBJ trick we've talked about or look at Object Reference you can see Landed Cost Receipt object is child of PO_Receipt_bus header object, that is you can do this:

Set oLCReceipt = oBusObj.AsObject(oBusObj.PO_LandedCostsReceiptObj)

Hopefully that will let you pass data in this direction and see the result in the Landed Cost grid.

2) When you want to SetStorageVar across a child object, you can't do the normal oScript.SetStorageVar(var,value)

Knowing that oScript is based on ScriptObject property of the business object and both of them have that property, try to reference the LC Rcpt ScriptObject with something like this:

Set oScript4LC = oSession.AsObject(oSession.AsObject(oBusObj.PO_LandedCostsReceiptObj).ScriptObject)

Then: 
If BlahBlahBlah Then nLCFreight = 50.00 'pretend
retVal = oScript4LC.SetStorageVar("varLCType","FRGHT")
retVal = oScript4LC.SetStorageVar("varFreightAmt",nLCFreight)

Now in your LC script use the normal oScript to GetStorageVar
sLCType = "" : nLCFrt = 0.00
retVal = oScript.GetStorageVar("varLCType",sLCType)
r=oScript.DebugPrint("sLCType = " & sLCType & " which should be FRGHT hopefully)
retVal = oScript.GetStorageVar("varFreightAmt", nLCFrt)
r=oScript.DebugPrint("nLCFrt = " & nLCFrt & " which should be 50 hopefully")

But try Option 1 first to create / send data.

Thanks for the ideas Alnoor! 

I'll test this when I get a chance, and report back with results.

Just fixed a typo in the Set oScript4LC line.

Thanks again Alnoor!

Here is the magic... using method #1 in a button script.  Oddly there is no AddLine() for the LCR business object, but SetKey allowed me to insert / update a row all in one step (so the script ends up being more streamlined without having to detect if there is an existing row for the CostType I want to set).

set oLCReceipt = oBusObj.AsObject(oBusObj.PO_LandedCostReceiptObj)
...
sKeyPadded = sReceiptType & sReceiptNo & sCostType
retVal = oLCReceipt.SetKey(sKeyPadded)
...

Woohoo! Way to go Kevin.