I've got a Mordheim warband and I've love to take some of the heroes into battle in a Warhammer Fantasy game. Is this possible?
Many of the characteristics are similar but is there a mechanism to create a points value and translate his skills?
There is no official method of doing this.
However at out local club we do things like this all the time as we often play casual games for fun.
I would advise looking for the lord/hero with the closest stat line and use his base points, make sure you don't have any lower stats that the codex character though. Use his equipment list for any items you have and for any items that character cant take but you have look to other entries starting with those closed the the characters you used as your base point. if you have a hero look at the other heroes but if you used a lord choice look at the other lords before the heroes.
Make sure you agree this with your opponent first, it would work best if both of you are trying to do this. And remember this type of thing is just for fun, don't expect it to be balanced or even competitive.