I have posted a request for info on the possibility of injecting 6DOF data into FGFS from PSX, and got a kind reply here (https://groups.google.com/forum/embed/?place=forum%2Fgefs-online&showsearch=false&showpopout=false&showtabs=false&hideforumtitle=true#!category-topic/gefs-online/general-discussion/ufEaMEcWl5I)
Unfortunately the reply shows there being yet no built in functionality for it, but there is some chance of finding a way around it :-)