Since a LED drops 2 - 2.5v across its junction I would think you could string 55 or so in series with a small value resistor to scrub off the rest and limit the current although I bet there is a chip that would do a better job of current regulation for a nickel a unit or less in the quantity.
I am not sure what the new white LEDs need to get to max illumination but I am guessing it is in the 20ma range.
(~24 watts)
