I'm not sure that you can.
Are you able to save a TIFF out of Paint Shop Pro?
#2
I think I saw that someone had made a plugin for that. No idea where or when.
#3
My Paintshop Pro format plugin is here <
http://telegraphics.com.au/sw/#pspformat>. Please note that it reads raster layers only (one at a time, due to Photoshop plugin API).
Google is here <
http://google.com/> (it's a great search engine, btw).
#4