The important question is what version of Premiere Elements are you using and on what computer operating system is it running?
If you have one of the versions that block still image import due to size, then you will need to batch crop/resize or just resize so that the total pixels per still do not exceed 16777261 pixels.
So before scaling thoughts...let us find out what we are dealing with...
a. What version of Premiere Elements are you using and on what computer operating system is it running?
b. What are the pixel dimensions (width in pixels x height in pixels) of the still images that you are trying to import into some version of Premiere Elements, especially the ones that are giving you the too large message. How many stills are involved in this project?
The secondary questions will be
a. What are your project settings?
b. What is your intended export?
The next phase will be "What to do about this situation?"
We will be watching for your details to help us help you.