Well if you're just spraying the TB you can remove the TB from the UIM and spray the TB away from the UIM. That way solvent won't get down there to the cats. just get a new TB gasket for replacement.
However, there are tiny EGR openings in the UIM that you may want to spray as well. Stuffing a rag down into there (back from the openings) and spraying that & the TB is a good route too.
