I agree with MichaelJ. It's feasible in two days if you want in the summertime, but with the snow conditions, it would be almost impossible right now. I would also suggest taking an evening to scoot up to Liberty Springs, then hitting the ridge the following morning; early mornings on Franc Ridge are phenomenal! From Lafayette to Galehead Hut is deceptively rugged--the trail maps won't do it justice as it's constant up and down over big, wet boulders (covered in snow right now). From Galehead, once you grunt up South Twin, it's fairly smooth sailing all the way to Crawford Notch, although, with fine views overlooking Zealand Notch and around Ethan Pond. Guyot Shelter, .7 miles from the AT is a great place to crash for the night, too, albeit adding 1.4 miles to your hike.
Let us know how it goes, whichever way you do it!