The only Arabic I'm familiar is what the "bad guys" speak in Call of Duty 4: Modern Warfare (an Xbox 360 video game, for anyone who doesn't know). So, I'm no reliable source, but maybe I can help a bit...
From what I can tell on Wikipedia and my limited familiarity with the sounds of Arabic, this does seem to be just a sort of "throaty R" which is what I guess you mean by Parisian /r/. If I'm not wrong, to pronounce this sound, put the 'base' of your tongue back into the back of your throat as if to make a regular "American R" but pull the tongue up in the back so that you're almost in the "hawk a loogey" position. Then just make the sound as if it were an R. Another way might be to be in the "ng" position as if saying the word "singing" or "banging" but open the back of the throat JUST enough to STOP airflow from entering the nose becoming nasal) and to ALLOW air to flow through the mouth.
In anatomical terms, the root of the tongue must be up against the pharynx. Fricative means it's a "flowing" sound that doesn't have an abrupt start or stop sound. Voiced means your vocal chords vibrate. Wikipedia says it's basically an approximant like English's L or R.
For comical reference, I imagine that if you trilled the Voiced Pharyngeal Fricative in the same way a Spanish speaker trills the R sound, it would sound a lot like a Wookie from Star Wars.
Hope that helps....?
EDIT:
Apparently, the "pharyngeal" version is very ambiguous and hard to pinpoint. The "voiced epiglottal stop" is the supposedly more common sound in Arabic, and is equally as confusing in pronunciation...
confused Also, check out these wiki pages if you haven't yet:
http://en.wikipedia.org/wiki/Ayin
http://en.wikipedia.org/wiki/Epiglottal_consonant
http://en.wikipedia.org/wiki/Epiglottal_stop
http://en.wikipedia.org/wiki/Epiglotto-pharyngeal_consonant
And you might check on the
Foreign Language Guild and try to track down a Gaia-friendly Arabic speaker.