The help file explains all of the requirements but the basics are: the Intel Fortran compiler and Visual Studio. I don't believer there is a way to write/use a user-subroutine in visual basic, they are with fortran or c++.
I meant to say visual studio. The help file says to use intel fortran compiler but I have fortran powerstation instead. I'd like to know if that would work too.
I use gcc - gfortran (linux), so I guess you can use other fortran compilers too. Just change the abaqus_v6.env file.
Change all references to ifort and icpc to "gfortran" and "gcc" (in my case, I don't know for you).