Premiere Elements can edit in standard video resolutions: 720x480, 1920x1080 and 4k.
It can not edit a project set up for 5760x1080.
I know your post is from a very long time ago.
Premiere Pro will allow you to create a custom 5760x1080 Sequence.
Rather than working with it at 5760x1080, have you considered presetting it as letterboxes inside of 1920x1080?
I've noticed that that is pretty common on YouTube.
The sample image is from Skid-Inc Gaming's PlanetSide 2 Part 1 (Triple Monitors / Eyefinity / Surround) [~4K] video:
Premiere Elements does not support custom sequence (project) settings. What PRE will do is adjust 5760x1080 clip to a 1920x1080 dimensional project. Width and height will adjust accordingly. The best you can do is to use handles to bring portions of the clip visible in 1920x1080 size. You should hold Shift key while dragging one of the handles of the clip to resize. This will maintain the aspect ratio of the clip.