Careful about this. Contrary to some popular belief, laminating a neck does not increase its strength. (Think about it -- if you took an ordinary maple neck, layered out a few .0005" slots and filled them with glue, the stiffness of the neck would not go up.) If anything, laminated necks get stiffer because people are replacing some of the maple content with stiffer woods such as purpleheart, wenge, pau ferro, bubinga and ebony.
If you use Will's suggestion, and make the entire assembly so that the air under the frets is a minimum, you should be ok. You will have to do your glue-up piece by piece, with a thin, removable spacer in the gap to simulate a fret - almost like doing a lined fretless. You'll have to do a test or two to get the right thickness spacer, as proven by the test piece fretting well. The difference between a .023" slot and a .025" slot can be significant.