Extract the LYT and VIS. Extract the MDL/MDXs and their matching WOKs. Decompile the models to ASCII with MDLEdit (if using KMax - KBlender can load the binary models directly). Put the files in a folder together. In order to have KMax actually import the models when loading a LYT, you need to tick the "With Models" checkbox and add in the filename filter so it can find them. In the case of MDLEdit, that will be "-mdledit":
For example, in the case of the Endar Spire Command Deck layout, m01aa.lyt, the first room model is "M01aa_01a" but the filename for the ASCII model (when decompiled with MDLEdit) is "m01aa_01a-mdledit.mdl.ascii", so you need to enter that suffix so that KMax knows to exclude it.
By the way, if you haven't already you will want to extract all the textures from the game (extract the TPCs and use TPCView to batch convert them to TGAs). Then in Max go to Customize -> Configure User Paths -> External Files and click the Add button to pop up a browser to select the folder where the textures are. Now KMax can automatically load the textures when loading a model.