(just some info to get us started).
To use the PS supplied object converter you need to get modeles into lightwave 5 format, which is old and not well supported. I (Jasper) am working on a new converter and have already done a PSO -> vairous formats converter - see http://pointless.net/eoc/ for some info.
That page also has a tool for generating .ftu and .ftc files - the texture format used by Flux.
If you use a 3d modeling package and want a converter for a file formats it supports get in touch with me and i'll see what i can do.
There is code in MaxScript for 3DSMax for importing .PSO to max here http://www.pixelosity.net/EOC/eoc.html