I have the following netlist file of c17 circuit 

.title c17.sp
.include '090.nmos'
.include '090.pmos'

.subckt nand2 3 1 2 9999
m1 3 1  9999 9999 gpdk090_pmos1v l=2u w=8u as=8p ad=8p ps=12u pd=12u
m3 3 2  9999 9999 gpdk090_pmos1v l=2u w=8u as=8p ad=8p ps=12u pd=12u
m2 3 1   4  0 gpdk090_nmos1v l=2u w=8u as=16p ad=16p ps=16u pd=16u
m4 4 2   0  0 gpdk090_nmos1v l=2u w=8u as=16p ad=16p ps=16u pd=16u
.ends nand2



x10 10 1 3 9999 nand2
x11 11 3 6 9999 nand2
x16 16 2 11 9999 nand2
x19 19 11 7 9999 nand2
x22 22 10 16 9999 nand2
x23 23 16 19 9999 nand2

.end

What I would like to ask is how I can instatiate the MOS transistors of the same nand gate  or of different ones to have different parameter values (e.g. L, W).

Parameter values are defined in the model file of the CMOS transistor and in the definion of the subcircuits. Can I redefine them when I instantiate the subcircuits?

thanx