Please let me know if I am misunderstanding your question:
You want to basically use a Vlookup, but the two workbooks can't communicate to each other, correct?
If they can, but you don't want them linked, you can simply use the vlookup formula and then copy and paste values to break the link. If they just can't communicate, then:
Read Excel
For each CurrentItem in ExcelData 'currentitem would be a row in this case
If CurrentItem[LookupHeader] = %CurrentVariableToMatch%
Set %FoundValue% to %CurrentItem[ReturnHeader]%
Exit(Loop)
End(IF)
End(Loop)
Above reads the table, so you are no longer working with Excel. In PAD, it is iterating through each row of the vlookup table. Put the Header name in the square brackets to tell it which value to pull. Get your Value out, exit the loop, then do what you need to with the value before the flow comes back to this loop and overwrites the value.
Good luck!