Help!!! Low Vt NMOS in TSpice

Hi to all,
I presently working on a research problem on wireless sensor Networks... I need to design a Dickson charge pump.. I plan to simulate it using TSpice.. However, I am facing certain problems due to lack of familiarity with the TSpice as well as the fact that I don't have that good background in NMOS...
I need to use a low Vt tansistor i.e. a low Vt NMOS.. How do I get that and use it in a TSpice simulation.. I understand why a low Vt NMOS is being used, but I lack the knowledge of full theory of NMOS(and I don't have much time as we are getting ready for a publication !!!!).. So the question is : How I get a low Vt NMOs using TSpice (I believe I need to do stg with W/L ratio for a standard 65 nm process ... ) And I would prefer not use L-Edit as I have never used that before.
Thanking all in advance...
Regards..
Shantanu Bhalerao
ECE,NIT Nagpur.

Hi santanu,
You need to include a low Vt model file in T-spice along with your normal model file.

Now when assigning names such as

M1 d g s b PMOS W=1u L=0.12u in normal transisters. Put name given in Low Vt model file such as lvt_PMOS in place of PMOS.