jefequeso: I have the same problem as OP. I'd really like to play and enjoy the game, but not being able to strafe or even use my precious WASD is kinda killing my enjoyment. So how do you use dosbox key mapping, and is it possible to add strafing with it? If not, it's not too big a problem... I just really want to be able to use WASD for movement of SOME sort :P
I don't have this game so i can't help you with an optimal mapper key scheme or something like that, but in regards to the mapper, you start the game and you hit CTRL + F1 to bring up the mapper and then it's just a matter of swapping things around by deleting and adding events to the keys you're moving around.
So, whatever function W has in the game, assign it to whatever key you wish and then assign the movement you want for W to the W key. Keep in mind you'll probably want to delete the events that are already assigned to the keys in question beforehand otherwise you'll have multiple events assigned to the same key and that's no good.
The mapper can be a bit confusing the first 5 minutes but it's really a tool taht's pretty easy to use, try to do a few simple swaps between two keys and you'll figure it out in no time.
In case you mess up the key assigment on the mapper and you want to start over, go to the game folder and delete the mapper.txt file - that will dispose of the mapper config and allow you to start remapping from scratch.