Exporting a 2.39 sequence to 16:9 anamorphic

been asked to deliver it as 16:9 anamorphic (squeezed).

I would question that request, as it would reduce the quality (resolution) of the original.  The ideal is square pixels, not the rectangular pixels required for anamorphic.

Here's one approach:

1. In the Project tab, right click on your current Sequence and choose New Sequence From Clip.  This will nest your current Sequence into a new, containing Sequence with the same name.
2. In the Project tab, add something like "Conform to 16x9 ProRes HQ" to the end of the Sequence name.
3. With the new, containing Sequence still selected in the Project tab, choose Sequence > Sequence Settings and change the following:
   • Editing Mode: Custom
   • Frame Size: 1920x1080
   • Preview File Format: QuickTime
   • Codec: Apple ProRes 422 HQ
   • If the Video Previews are not set to 1920x1080, click "Reset" to do so.
   • Then click OK. (Premiere may present a dialog box stating the Preview files need to be deleted, click OK or Yes.)
4. In the Timeline tab, select the nested Sequence.
   • In the Effect Controls for the selected nested Sequence, uncheck "Uniform Scale".
   • Set the Scale Height to 125.6 and the Scale Width to 93.8.
5. When you export your containing Sequence (File > Export > Media), enable "Match Sequence Settings".  Set the Output Name and location as you would normally and then click either Queue or Export.