I would also like to do this - specifically incorporating an image file (png, jpg etc) into a Journal that is generated using a JSL script. Is it possible? The journal then gets exported as HTML so the image would need to be kept in this export.
This blog entry (see link below) discusses the topic somewhat. It appears that it is not possible to insert an existing image by jsl-script in JMP 8, but JMP 9 may see some improvements in this area according to he author.
Apparently an image can be dropped or pasted into a JMP window (however, it does not seem to work on the Mac, I just get the file's icon embedded instead of its image).
Of course an image can be drawn from scratch using jsl but I guess that's not what you are after.