I created a symbol for a CNFET then tried the Stanford model file (copied to the LTS "sub" folder in LTspice but had problems.
The file includes (at line 74) ".LIB CNFET" which needs to be modified or commented out, otherwise LTS can't open the file.
LTS also reported (e.g. at lines 509 et seq) many "Mismatched single quotes" errors which seemed to arise from line continuations (use of + symbol). I fixed a few but then gave up. With persistence you may get the model file correct and working. Good luck.