With Lightoom in the Develop module, select the images you want to merge in the filmstrip and with the cursor over one of the images in the filmstrip right click (windows) and select Edit in and select the merge in Photoshop. I assume this works with Elements, I do it with Potoshop CS6.
I am not sure if there is a direct option from Lightroom but you could open the files in Photoshop Elements, then select File-> New > Photomerge Panorama and select Add Open Files from the dialog. for the rest have a look at http://helpx.adobe.com/photoshop-elements/using/stitching-together-panoramas.html
And again I am not sure if the merged file will automatically be placed in the LR Catalog but you could save it to the directory and then synchronise to get it into the cat.
When in LR you can select multiple files then right-click and choose Edit in Photoshop Elements (or Other Application and configure PhotoshopElementsEditor.exe as that application) which will open the selected files in Elements and then follow the process outlined on the previously mentioned Adobe HelpX page.
Thanks for everyone's reply.
So what I gathered from reading these replies is that: (1) I can edit the photos in LR, save them somewhere on my laptop, and then open the edited photo in PSE to create a panorama. Is this correct?
Alternatively, (2) I can configure "PhotoshopElementsEditor.exe" so that I would be able to select "Merge to Panorama in PSE" from the Edit-in dropdown menu in LR. Is this also correct? If so, how do I configure "PhotoshopElementsEditor.exe"?
I recently purchased a DSLR and I never used LR or PSE, so any help is greatly appreciated. Thanks.
I can configure "PhotoshopElementsEditor.exe" so that I would be able to select "Merge to Panorama in PSE" from the Edit-in dropdown menu in LR. Is this also correct?
No, that is incorrect. You can instruct LR to send the images to PSE 12 (as a copy with LR adjustments, psd or tiff, 8 bits because PSE will not make panos from 16 bit images) , but once they have appeared in the tray at the bottom of PSE's screen you have to select them and then open Photomerge: Pano from the Enhance menu.
how do I configure "PhotoshopElementsEditor.exe"?
In LR right-click on an image and select Edit In. You should see "Photoshop Elements Editor". If not, open the Preferences (Edit menu) and go to the External Editing tab. Set PSE as the second choice there.