Well, I've thought about this alot myself; I started in WoD before I started playing D&D heavily, and the D&D rules for vampires have always seemed a little restrictive if you want more "literary" vampires.
The Ravenloft core book has some nice mechanics for sprucing up most of the undead, including vampires, and the five categories they give allow for little to no change in your "status" as dictated by the categories. It wouldn't be too hard to modify the table slightly to allow for a natural progression from one category to the next, or for a more abrupt progression similar to that espoused by Diablerie. I've been thinking about modifying the table for such a natural progression.
Disciplines could be modified into Special Attacks and Special Qualities which increase with usage, age, or both. Some of the Disciplines already have natural correlates -- Natural Armor and Damage Reduction map well onto Fortitude, increases in Dexterity (such as cat's grace, or inherent/enhancement bonuses) can simulate Celerity to a fair degree, and one can draw similar correlations between Potence and Strength & Strength enchancing spells.
Some of the lower-level powers of Animalism are also already written right into the vampire template (calling and directing animals) and the domination effects of the vampire template are similar in nature to some powers of Dominate and Animalism. Some of the more esoteric Disciplines (Obtenebration, Thaumaturgy, Vicissitude) can only really be simulated using spells, spell-like abilities, and special qualities without really overhauling the system to include them. Making them Skills might work, but there would have to some amount of differentiating between normal skills and these vampiric skills in a manner similar to that of WoD; Discipline increases cost SO much more than Skill increases, and without a similar cost, vampires using Disciplines as skills would come to quickly dominate the story.
Barbarian Rage, modified slightly, could make a fair simulation of the Frenzy mechanics from WoD.
Blood Points are also kinda written right into the template -- the Blood Drain ability. I'd prolly modify it so that a vampire can use these stolen "points" of Constitution to power their special abilities.
How would you manage mechanics like Humanity and Willpower, though? By just exporting the powers, you kinda lose the feel they originally create and just turn them into "WOW" factors. I think that a big shock to your vamp-hunters might be that some vampires aren't inherently evil, and aren't necessarily trying to eat everyone and everything with which they come in contact.
