As far as simple Pathfinderization:
Requirements: Change the skill requirements to Knowledge (arcana) 5 ranks, Perform (oratory) 1 rank, and Spellcraft 1 rank.
Class skills: Change the skill list to Acrobatics, Climb, Craft, Diplomacy, Knowledge (all), Perception, Profession, Sense Motive, Spellcraft, Swim, and Use Magic Device.
Spellcasting: Leave as-is. Be sure to import the power word spells from that book to your game to make the class usable.
Draconic Words: Ocuir grants the bonus to Perception checks based on sight.
That's it, basically. I'll look over the new power word spells to see if they need to be changed.
So the power word spells all seem fine, with the exception of power word pain, which is just cheese if you take it at first level. Then again, sleep is cheese at 1st level, and PW:pain requires at least 2 rounds to actually kill most CR 1 foes. Also, both spells rapidly become useless as you gain levels.
So I guess it's not really as cheese as some have suggested in the past.
Given the nature of multiclassing and such in Pathfinder, it might be a better option as an archetype or bloodline for Sorcerers. I'll poke around at it when I get home and see if I can put something together =)
Now on to the question of whether it needs mechanical changes to fit into the higher power curve of Pathfinder.
I would say that allowing full spellcasting progression (+1 at every level including 1st) would be a fine compromise. This class allows free metamagic all day every day for certain specific types of spells and a few specific feats. The earlier draconic words might seem underwhelming, but they are actually quite powerful due to their unlimited use (though of course you can only affect a particular creature once per day). Ordinarily I would keep the described spellcasting progression, but being two levels behind the wizard rather than one renders spontaneous casters almost useless, and since only they can use this PrC, and spontaneous casters now have more class features other than spellcasting, I'd say it's fine in Pathfinder.
A few other small possible tweaks:
Renthisj allows a spell to be Stilled for free if you have the Still Spell feat and 4 or more levels of Dracolexi. Since draconic words cost a swift action, it's not really better than something like Arcane Armor Training.
Osvir uses your spontaneous arcane caster level rather than Dracolexi level for determining if a target is frightened. If its Hit Dice are equal to or less than your Dracolexi level, it becomes panicked instead.
Valignat, used straight rather than as metamagic, sets the target on fire in addition to the 5d6 fire damage.
I always found this prestige class particularly fascinating, especially in the context of later 3.5, when the developers finally realized how terrible the sorcerer was in comparison to the wizard when the DM was inexperienced, and how much more popular the sorcerer had become than the wizard.
Sounds fine.