In reply to ianghogg:
Bit late, but might help someone.
1) Use hacksaw /sharp knife to cut around external plastic sheath + remove
2) Continue to use hacksaw to 'score' about 30% into metal wire casing of brake cable (all the way round, you don't need to try and cut through them)
3) Take each individual metal wire in the casing and bend outwards. If you have scored correctly they will just snap off!
4) Cut through internal sheath with wire cutters.
Done! Its a much quicker process than I've made it sound. Obviously not as good as some park tool cutters, but free and significantly easier than trying to hacksaw/cut through the cables without the correct tools!