Assigning material permittivity which is a function of frequency and have to load data from .DAT file

Hi
I am struggling with a problem. I have a .dat file which contains three column.col 1 is for frequency col 2 is for epsilon_single prime and col 3 is for epsilon_double prime....
1)how can i assign col 1 as frequency variable in comsol?
2)how can i assign col 2 and col 3 as the input of complex permittivity in a material's permittivity parameter as (epsilon_prime-j*epsilon_double prime)
Thanks in advance.
Saimoom