I can't figure out a good way to directly get from L3DT to 3ds max but I have found a pretty good solution.
Create your terrain in L3DT.
Export the heightmap (I prefer png over jpeg for quality but it doesn't matter)
In 3ds max create a square plane of whatever size you want and create a large amount of subdivisions (I tend to use a plane size of 1000 x 1000 units with 100 x 100 divisions. The more divisions the greater the quality.)
Apply a displace modifier to your plane and using your exported heightmap for the bitmap. I usually set the strength somewhere between 50 and 150, so experiment to find the result for you. Just keep in mind when adjusting the strength that if your going to create multiple planes with mosaics to use the same strength so that they'll line up.
Apply the texture: You can go about this different ways depending on how much quality you want.
Simply export the texture created in L3DT and apply it to the plane through the material manager.
Export alpha maps of the textures. Then, using Max's material editor, create a texture that is a “Multi/Sub-Object” as opposed to “Standard”. Then for each alpha map/texture that you have create a blended material with the first layer being the texture you want, the second layer being none, and the mask being the alpha map. This way takes more time but will give you much higher quality.
It wouldn't be too hard to create a plugin that would follow those steps for you, but I was too lazy to write one 
. I hope that helps.
