If you're asking to shorten the actual clips -- that's not as easy as you'd think.
About the only way to do it is to open an AVCHD project in Premiere Elements, import the video into it, place the clip on the timeline and trim it, then use Share/Computer/MPEG 1440x1080 to export a short version of the clip -- then delete the original from your hard drive.
Sorry, but there's no way to just take existing clips and make them shorter.
I think that is exactly what I did on my initial tests. I only opened one raw clip, trimmed it in the timeline, and then saved it as an MPEG. There were a few different quality options in the list and I wasn't sure which one would give me the best quality image (no image quality loss).
So, if I created a new project, dragged thirty clips into the import field, I could then put one at a time in the timeline, trim and save? Then remove the first clip from the timeline and put in another one, trim and save? I'd only need one Project and would continually be adding and deleting files in it. Seems logical with my limited experience with Premiere.
I sometimes set up a tripod with the video camera and start filming a moose resting under a fall tree. I set up another tripod and photograph him with a still camera. The video might run for 5 minutes, but have essentially nothing unique on it but maybe him shaking the leaves off his antlers. I'd only want to save that little segment and dump the other 4 and a half minutes. As another example, I might have five minutes of an Oxbow Bend sunrise in Grand Teton National Park. The only part I might want to keep is the shortened clip where a flock of geese fly through the scene.
Yes, you can load all of the clips into the same project and then trim them one at a time on the timeline, M.
In fact, that's probably the best solution!
If you're using the proper project settings for your source footage, Sharing your trimmed video as 1440x1080 MPEGs should give you virtually no change in video quality. Certainly none noticeable.
You will then be able to load those video clips into a project set up for HDV video and they should work beautifully!
This will help take some of the uncertainty off going forward with my trimmng project.