Perform Quick FInd should work just fine with IWP. The show Custom Dialog step, however, is not IWP compatible. (You can check to see what script steps are IWP compatible by selecting that option in the "Show Compatibility" drop down in the lower left corner of the dialog you've posted here.)
Just put Table::Search directly on a layout so that the user can enter search data there instead of in the custom dialog and place a button next to it to perform a script of just lines 2 and 3 of what you show above and it should work in IWP.
here is what the box looks like when I hit "LOOK UP"
Based on the script above could you show me what the script you mentioned should look like?
AND HERE IS THE SCRIPT FOR IT
Just put Table::Search directly on your layout. Then delete the first line, the one with show custom dialog from your script.