I created a new material and provided a converter to Kam's material
Not all things are supported yet but you should be able to import pretty much any GTA dff from any platform. That does *not* include iOS LCS dffs (yet) as they're not proper dffs.
Note that models exported by Kam's script don't get different materials per mesh as Kam exports material IDs wrong. I will correct this in a future version but was too lazy to do it now.
EDIT: As of version 2.0 there is an exporter now as well. Not everything that is imported can be exported yet, but I wanted to get this thing out.
See the README for some more information.
The "convert hierarchy" option should be left on. When exported in world space the official RW exporter rotates everything so max's z-up will match RW's y-up world. Models that were originally exported from max's biped objects are exported "lying down" when not exported in world space. This option rotates them so it'll look nicer.