Please post to the mail list, not to me.
I thought you were asking about the COMPASS force field
since you mentioned cross terms which I assmed
were things like bond/angle interactions.
In LAMMPS lingo that is the class2 FF, see the CLASS2 package.
If you just want the harmonic and cvff styles you list, then
just look at those doc pages and they should tell you exactly
what coeffs need to be in the data file or set in your input script.